GIFT  OF 
Author 


A  PLEA  FOR  GREATER  SIMPLICITY 
IN  THE  LANGUAGE  OF  SCIENCE. 


BY 
T.   A.   RICKARD. 


[Keprinted  from  SCIENCE,  N.  £,  Vol.  XV.,  No.  369, 
Pages  182-139,  January  $4.,  1902.'] 


JL 


[Reprinted  from  SCIENCE,  N.  8.t  Vol.  XV.,  No  369,      — r-i   »   .  ..   -. 
iges  132-139,  January  24,  1902.]  )  VN  \UrL 


Pages 


A  PLEA  FOR  GREATER  SIMPLICITY  IN  THE       \^>9  \ 
LANGUAGE  OF  SCIENCE*  M  As\ 

SCIENTIFIC  ideas  are  with  difficulty  solu- 
ble in  human  speech.  Man,  in  his  contempla- 
tion of  the  flux  of  phenomena  at  work  all 
about  him,  is  embarrassed  by  the  want  of  a 
vehicle  of  thought  adequate  for  expression,  as 
a  child  whose  stammering  accents  do  not  per- 
mit him  to  tell  his  mother  the  new  ideas 
which  suddenly  crowd  upon  him  when  he 
meets  with  something  alien  to  his  experience. 

Our  knowledge  of  the  mechanism  of 
nature  has  been  undergoing  a  process  of 
growth,  much  of  which  has  been  sudden. 
It  is  not  surprising,  therefore,  that  the  in- 
completely formed  ideas  of  science  should 
become  translated  into  clumsy  language 
and  that  inexact  thinking  should  be  evi- 
denced by  vagueness  of  expression.  This 
inexactness  is  often  veiled  by  the  liberal 
use  of  sonorous  Greek-Latin  words. 

The  growth  of  knowledge  has  required 
an  increase  in  the  medium  of  intellectual 
exchange.  New  conceptions  have  called 
for  new  terms.  Sir  Courtenay  Boyle  has 
pointed  out  that  the  purity  of  a  nation's 
coinage  is  properly  safeguarded,  while  the 
verbal  coinage  of  its  national  language  is 
subject  to  no  control.  Specially  quali- 
fied persons  prepare  the  standards  of  gold 
and  silver.  This  insures  the  absolute 
purity  of  the  measures  of  commercial  ex- 
change and  gives  the  English  sovereign 
and  the  American  gold  piece,  for  example, 
an  assured  circulation  along  all  the  ave- 
nues of  commerce.  It  is  not  so  with  the 
standards  of  speech.  The  nation  debases 

*A  paper  read  before  Section  E  of  the  Ameri- 
can Association  for  the  Advancement  of  Science, 
August  28,  1901. 


••  ,  •* 


3  „•.  :r;i  3 
V-  '      ,  v  ::•':%„• 


2 


Its  language  with  slang,  with  hybrid  and 
foreign  words,  the  impure  alloys  and  the 
cheap  imports  of  its  verbal  coinage,  mere 
tokens  which  should  not  be  legal  tender  on 
the  intellectual  exchanges.  Prance  has  an 
academy  which  in  these  matters  has  much 
of  the  authority  given  to  the  Mint,  whose  as- 
sayers  test  our  metal  coins;  but  in  our  coun- 
try the  mintage  of  words  is  wholly  unre- 
stricted, and,  as  a  consequence,  the  English 
language,  circulating  as  it  does  to  all  the 
four  corners  of  the  globe,  has  received  an 
admixture  of  fragments  of  speech  taken 
from  various  languages,  just  as  the  cur- 
rency with  which  one  is  paid  at  the  fron- 
tier, where  empires  meet,  includes  the  coin- 
age of  several  governments,  each  of  which 
passes  with  an  equally  liberal  carelessness. 
Science  ignores  geographical  lines  and 
bemoans  the  babel  of  tongues  which  hin- 
ders the  free  interchange  of  ideas  between 
all  the  peoples  of  the  earth.  Nevertheless, 
the  international  character  of  technical 
literature  is  suggested  by  the  fact  that 
three  languages,  French,  German  and 
English,  are  practically  recognized  as  the 
standard  mediums  of  intellectual  exchange. 
One  of  these  affords  the  most  lucid  solvent 
of  thought,  another  is  the  speech,  of  the 
most  philosophical  of  European  people  and 
the  third  goes  with  world-wide  dominion, 
so  that  each  has  a  claim  to  become  the 
recognized  language  of  science.  The 
brotherhood  of  thinking  men  will  have 
been  fully  recognized  when  all  agree  to 
employ  the  same  tongue  in  their  inter- 
course, but  such  a  'far-off  divine  event' 
is  not  within  the  probabilities  of  the  pres- 
ent, consequently  there  remains  only  for 
us  to  make  the  best  of  our  own  particular 
language  and  to  safeguard  its  purity,  so 


3 

that  when  it  goes  abroad  the  people  of 
other  countries  may  at  least  be  assured 
that  they  are  not  dealing  with  the  debased 
currency  of  speech. 

Barrie  has  remarked  that  in  this  age  the 
man  of  science  appears  to  be  the  only  one 
who  has  anything  to  say— and  the  only  one 
who  does  not  know  how  to  say  it.  It  is 
far  otherwise  in  politics,  an  occupation 
which  numbers  among  its  followers  a  great 
many  persons  who  have  the  ability  for 
speaking  far  beyond  anything  worth  the 
saying  that  they  have  to  say.  Nor  is  it  so 
in  the  arts,  the  high  priests  of  which,  ac- 
cording to  Huxley,  have  '  the  power  of  ex- 
pression so  cultivated  that  their  sensual 
caterwauling  may  be  almost  mistaken  for 
the  music  of  the  spheres. '  In  science  there 
is  a  language  as  of  coded  telegrams,  by  the 
use  of  which  a  limited  amount  of  informa- 
tion is  conveyed  through  the  medium  of 
six-syllabled  words.  Even  when  not  thus 
overburdened  with  technical  terms  it  is 
too  often  the  case  that  scientific  concep- 
tions are  conveyed  in  a  raw  and  unpala- 
table form,  mere  indigestible  chunks  of 
knowledge,  as  it  were,  which  are  apt  to 
provoke  mental  dyspepsia.  Why,  I  ask, 
should  the  standard  English  prose  of  the 
day  be  a  chastened  art  and  the  writing  of 
science,  in  a  great  scientific  era,  merely  an 
unkempt  dressing  of  splendid  ideas?  The 
luminous  expositions  of  Huxley,  the  occa- 
sional irradiating  imagery  of  Tyndall,  the 
manly  speech  of  Le  Conte,  and  of  a  very 
few  others,  all  serve  simply  to  emphasize 
the  fact  that  the  literature  of  scientific  re- 
search as  a  whole  is  characterized  by  a  flat 
and  ungainly  style,  which  renders  it  dis- 
tasteful to  all  but  those  who  have  a  great 
hunger  for  learning. 


To  criticism  of  this  sort  the  profession- 
al scientist  can  reply  that  he  addresses 
himself  not  to  the  public  at  large,  but  to 
those  who  are  themselves  engaged  in  simi- 
lar research,  and  he  may  be  prompted  to 
add  to  this  the  further  statement  that  he 
cannot  pitch  the  tone  of  his  teaching  so  as 
to  reach  the  unsensitive  intelligence  of  per- 
sons who  lack  a  technical  education.  Fur- 
thermore, he  will  claim  that  he  cannot  do 
without  the  use  of  the  terms  to  which 
objection  is  made.  However,  in  condemn- 
ing the  needless  employment  of  bombastic 
words  of  classical  origin,  in  place  of  plain 
English,  I  do  not  wish  to  be  understood  as 
attacking  all  technical  terms.  They  are 
a  necessary  evil.  Some  of  them  are  instru- 
ments of  precision  invented  to  cover  par- 
ticular scientific  ideas.  Old  words  have 
associations  which  sometimes  unfit  them  to 
express  new  conceptions  and  therefore 
fresh  words  are  coined.  The  complaint 
lodged  against  the  pompous,  ungainly 
wordiness  of  a  large  part  of  the  scientific 
writing  of  the  day  is  that  it  is  an  obstacle 
to  the  spread  of  knowledge. 

Let  us  consider  the  subject  as  it  is  thus 
presented.  In  the  first  place,  does  the  ex- 
cessive use  of  technical  terms  impede  the 
advancement  of  science?  I  think  it  does. 
It  kills  the  grace  and  purity  of  the  litera- 
ture by  means  of  which  the  discoveries  of 
science  are  made  known.  Buskin,  himself 
a  most  accurate  observer  of  nature,  and 
also  a  geologist,  said  that  he  was  stopped 
from  pursuing  his  studies  'by  the  quite 
frightful  inaccuracy  of  the  scientific  peo- 
ple's terms,  which  is  the  consequence  of 
their  always  trying  to  write  mixed  Latin 
and  English,  so  losing  the  grace  of  the  one 
and  the  sense  of  the  other.'  But  grace  of 


diction  is  not  needed,  it  may  well  be  said; 
that  is  true,  and  it  is  also  true  that  a  clear, 
forceful,  unadorned  mode  of  expression  is 
more  difficult  of  attainment  and  more  de- 
sirable in  the  teaching  of  science  than 
either  grace  or  fluency  of  diction.  One 
must  not,  as  Huxley  himself  remarks, 
{  varnish  the  fair  face  of  Truth  with  that 
pestilent  cosmetic,  rhetoric,'  and  Huxley 
most  assuredly  solved  the  problem  of  how 
to  avoid  rhetorical  cosmetics  and  yet  con- 
vey deep  reasoning  on  the  most  complex  of 
subjects  in  addresses  which  are  not  only  as 
clear  as  a  trout  stream,  but  are  also  bright- 
ened by  warm  touches  of  humanity,  keen 
wit  and  the  glow  of  his  own  courageous 
manhood.  Nevertheless,  though  clearness 
of  expression  be  the  first  desired,  yet  grace 
is  not  to  be  scorned.  When  you  have  a 
teaching  to  convey,  it  is  well  to  employ  all 
the  aids  which  will  enable  you  to  get  a 
sympathetic  hearing.  Man  lives  not  by 
bread  alone,  much  less  by  stones.  He  likes 
his  mental  food  garnished  with  a  sauce. 
Let  the  cooking  be  good,  of  course,  but  a 
chef  knows  the  value  of  a  well-seasoned 
adjunct  to  the  best  dish. 

Our  language  is  capable  of  a  grace  and 
a  finish  greater  than  we  give  it  credit.  That 
it  is  possible  to  write  on  geology,  for  in- 
stance, in  the  most  exquisite  simple  Eng- 
lish has  been  proved  by  Ruskin,  whose 
'Deucalion'  and  'Modern  Painters'  con- 
tain many  pages  describing  accurately 
the  details  of  the  structure  of  rocks  and 
mountains,  and  dealing  with  their  geologic- 
al features  in  language  which  is  marked 
by  the  most  sparing  use  of  words  which 
have  not  an  Anglo-Saxon  origin. 

The  next  aspect  of  the  enquiry  is 
whether  the  language  of  science,  apart 


from  the  view  of  mere  grace  of  style  in 
literature,  is  not  likely,  in  its  present 
everyday  form,  to  delay  the  advance  of 
knowledge  by  its  very  obscurity.  Leaving 
the  reader's  feelings  out  of  the  argument, 
for  the  present,  it  seems  obvious  that  the 
whole  purpose  of  science,  namely,  the 
search  after  truth,  which  is  best  advanced 
by  accuracy  of  observation  and  exactness 
of  statement,  is  hindered  by  a  phraseology 
which  sometimes  means  very  much  but 
oftener  means  very  little,  and,  on  the 
whole,  is  most  serviceable  when  required 
as  a  cloak  for  ignorance.  To  distinguish 
between  what  we  know  and  what  we  think 
we  know,  to  comprehend  accurately  the 
little  that  we  do  know,  surely  these  are 
the  foundations  of  scientific  progress.  If 
a  man  knows  what  a  thing  really  is,  he  can 
say  so,  describing  it,  for  example,  as  being 
black  or  white;  if  he  does  not  know,  he 
masks  his  ignorance  by  stating  in  a  few 
Greek  or  Latin  terms  that  it  partakes  of 
the  general  quality  of  grayness.  Writers 
get  into  the  habit  of  using  words  that  they 
do  not  clearly  understand  themselves  and 
which,  as  a  consequence,  must  fail  in  con- 
veying an  exact  meaning  to  their  readers. 
Many  persons  who  possess  only  the  smat- 
tering of  a  subject  are  apt  to  splash  all 
over  it  with  words  of  learned  sound  which 
are  more  quickly  acquired,  of  course,  than 
the  reality  of  knowledge.  Huxley  said 
that  if  a  man  does  really  know  his  subject 
1 '  he  will  be  able  to  speak  of  it  in  an  easy 
language  and  with  the  completeness  of  con- 
viction, with  which  he  talks  of  an  ordinary 
everyday  matter.  If  he  does  not,  he  will 
be  afraid  to  wander  beyond  the  limits  of 
the  technical  phraseology  which  he  has 
got  up."  If  any  scientific  writer  should 


complain  that  simplicity  of  speech  is  im- 
practicable in  dealing  with  essentially 
technical  subjects,  I  refer  him  to  the  course 
of  lectures  delivered  by  Huxley  to  working- 
men,  lectures  which  conveyed  original  in- 
vestigations of  the  greatest  importance  in 
language  which  was  as  easily  understood  by 
his  audience  as  it  was  accurate  when  regard- 
ed from  a  purely  professional  standpoint. 

Science  has  been  well  denned  as  '  organ- 
ized common  sense ' ;  let  us  then  express  its 
findings  in  something  better  than  a  mere 
jargon  of  speech  and  avoid  that  stupidity 
which  Samuel  Johnson,  himself  an  arch- 
sinner  in  this  respect,  has  fitly  described 
as  'the  immense  pomposity  of  sesquipeda- 
lian verbiage.'  George  Meredith,  a  great 
mint-master  of  words,  has  recorded  his 
objection  to  '  conversing  in  tokens  not 
standard  coin. '  Indeed  the  clumsy  latinity 
of  much  of  our  scientific  talk  is  an  inherit- 
ance from  the  schoolmen  of  the  past;  it  is 
the  degraded  currency  of  a  period  when 
the  vagaries  of  astrology  and  alchemy 
found  favor  among  intelligent  men. 

Vagueness  of  language  produces  loose- 
ness of  knowledge  in  the  teacher  as  well  as 
the  pupil.  Huxley,  in  referring  to  the  use 
of  such  comprehensive  terms  as  '  develop- 
ment' and  'evolution,'  remarked  that 
words  like  these  were  mere  'noise  and 
smoke/  the  important  thing  being  to  have 
a  clear  conception  of  the  idea  signified  by 
the  name.  Examples  of  this  form  of  error 
are  easy  to  find.  The  word  *  dynamic '  has 
a  distinct  meaning  in  physics,  but  it  is 
ordinarily  employed  in  the  loosest  possible 
manner  in  geological  literature.  Thus,  the 
origin  of  a  perplexing  ore  deposit  was  re- 
cently imputed  to  the  effects  produced  by 
the  '  dynamic  power '  which  had  shattered 


8 

a  certain  mountain.  '  Dynamic r  is  of 
Greek  derivation  and  means  power ful, 
therefore  a  'powerful  power '  had  done 
this  thing ;  but  in  physics  the  word  is  used 
in  the  sense  of  active,  as  opposed  to  '  static r 
or  stationary,  and  it  implies  motion  result- 
ing from  the  application  of  force.  In  the 
ease  quoted,  and  in  many  similar  instances, 
the  word  '  agency '  or  *  activity '  would 
serve  to  interpret  the  hazy  idea  of  the 
writer,  and  there  is  every  reason  to  infer, 
from  the  context,  that  he  substituted  the 
term  '  dynamic  power  'merely  as  a  frippery 
of  speech.  It  is  much  easier  to  talk  grand- 
iloquently about  a  '  dynamic  power '  which 
perpetrates  unutterable  things  and  recon- 
structs creation  in  the  twinkling  of  an  eye 
than  it  is  to  make  a  careful  study  of  a 
region,  trace  its  structural  lines  and  de- 
cipher the  relations  of  a  complicated  series 
of  faults.  When  this  has  been  done  and  a 
writer  uses  comprehensive  words  to  sum- 
marize activities  which  he  has  expressly 
denned  and  described,  then  indeed  he  has 
given  a  meaning  to  such  words  which  war- 
rants him  in  the  use  of  them. 

In  this  connection  it  is  amusing  to  re- 
member how  Ruskin  attacked  Tyndall  for 
a  similar  indiscretion.  The  latter  had  re- 
ferred to  a  certain  theory  which  was  in 
debate,  and  had  said  that  it,  and  the  like 
of  it,  was  '  a  dynamic  power  which  operates 
against  intellectual  stagnation/  Ruskin 
commented  thus :  ' '  How  a  dynamic  power 
differs  from  an  undynamic  one,  and,  pre- 
sumably, also,  a  potestatic  dynamis  from 
an  unpotestatic  one— and  how  much  more 
scientific  it  is  to  say,  instead  of— that  our 
spoon  stirs  our  porridge— that  it  '  operates 
against  the  stagnation  of  our  porridge/ 
Professor  Tyndall  trusts  the  reader  to 
recognize  with  admiration." 


Among  geological  names  there  is  that 
comfortable  word  '  metasomatosis '  and  its 
offspring  of  'metasomatic  interchange' 
'  metasomatie  action, '  '  metasomatie  origin, ' 
etc.,  etc.  To  a  few  who  employ  the  term  to 
express  a  particular  manner  in  which  rocks 
undergo  change,  it  is  a  convenient  word 
for  a  definite  idea,  but  for  the  greater 
number  of  writers  on  geological  subjects 
it  is  a  wordy  cloud,  a  nebular  phrase, 
which  politely  covers  the  haziness  of  their 
knowledge  concerning  a  certain  phenom- 
enon. When  you  don't  know  what  a  thing 
is,  call  it  a  '  phenomenon ' !  Instances  of 
mere  vulgarity  of  scientific  language  are 
too  numerous  to  mention.  '  Auriferous ' 
and  '  argentiferous '  are  ugly  words.  They 
are  unnecessary  ones  also.  The  other  day 
a  metallurgical  specialist  spoke  of  '  aurifer- 
ous amalgamation'  as  though  any  process 
in  which  mercury  is  used  could  be  gold- 
bearing  unless  it  was  part  of  the  program 
that  somebody  should  add  particles  of  gold 
to  the  ore  under  treatment.  A  mining 
engineer,  of  the  kind  known  to  the  press 
as  an  expert,  described  a  famous  lode  as 
traversing  '  on  the  one  hand  a  feldspathic 
tuf  aceous  rock '  and  '  on  the  other  hand  a 
metamorphic  matrix  of  a  somewhat  argillo- 
arenaceous  composition.'  This  is  scientific 
nonsense,  the  mere  travesty  of  speech.  To 
those  who  care  to  dissect  the  terms  used  it 
is  easily  seen  that  the  writer  of  them  could 
make  nothing  out  of  the  rocks  he  had  ex- 
amined, save  the  fact  that  they  were  de- 
composed and  that  the  rock  which  he  de- 
scribed last  might  have  been  almost  any- 
thing, for  all  he  said  of  it;  for  his  de- 
scription, when  translated,  means  literally 
a  changed  matter  of  a  somewhat  clayey- 
sandy  composition,  which,  in  Anglo-Saxon, 


10 


is  m-u-d!  The  'somewhat*  is  the  one  use- 
ful word  in  the  sentence.  Such  language 
may  be  described  in  the  terms  of  miner- 
alogy as  metamorphosed  English  pseudo- 
morphic  after  blatherskite.  Some  years 
ago,  when  I  was  at  a  small  mine  near 
Georgetown,  in  Colorado,  a  professor 
visited  the  underground  workings  and  was 
taken  through  them.  He  immediately  be- 
gan to  make  a  display  of  verbal  fireworks 
which  bewildered  the  foreman  and  the 
other  miners  whom  he  met  in  the  mine,  all 
save  one,  a  little  Cornishman,  who,  bring- 
ing him  a  bit  of  the  clay  which  accom- 
panied one  of  the  walls  of  the  lode,  said  to 
him,  'What  do  'ee  call  un,  you?'  The 
professor  replied,  '  It  is  the  argillaceous 
remnant  of  an  antediluvian  world.'  Quick 
as  a  flash  came  the  comment,  *  That's  just 
what  I  told  me  pardner.'  He  was  not  de- 
ceived by  the  vapor  of  words. 

Next  consider  the  position  of  the  reader. 
It  is  scarcely  necessary  at  this  date  to  plead 
for  the  cause  of  technical  education  and 
the  generous  bestowal  of  the  very  best  that 
there  is  of  scientific  knowledge.  The  great 
philosophers  of  that  New  Reformation 
which  marked  the  era  of  the  publication  of 
*  The  Origin  of  Species '  have  given  most 
freely  to  all  men  of  their  wealth  of  learn- 
ing and  research.  When  these  have  given 
so  much  we  might  well  be  less  niggardly 
with  our  small  change  and  cease  the  prac- 
tice of  distributing,  not  good  wholesome 
intellectual  bread,  but  the  mere  stones  of 
knowledge,  the  hard  fossils  of  what  were 
once  stimulating  thoughts.  In  the  ancient 
world  the  Eleusinian  mysteries  were  with- 
held from  the  crowd  and  knowledge  was 
the  possession  of  a  few.  Do  the  latter  day 
priests  of  science  desire  to  imitate  the  at- 


11 

tendants  of  the  old  Greek  temples  and  con- 
fine their  secrets  to  a  few  of  the  elect  by 
the  use  of  a  formalism  which  is  the  mere 
abracadabra  of  speech?  Among  certain 
scientific  men  there  is  a  feeling  that  scien- 
tists should  address  themselves  only  to 
fellow  scientists,  and  that  to  become  an 
expositor  to  the  unlearned  is  to  lose  caste 
among  the  learned.  It  is  the  survival  of 
the  narrow  spirit  of  the  dark  ages,  before 
modern  science  was  born.  There  are  not 
many,  however,  who  dare  confess  to  such 
a  creed,  although  their  actions  may  occa- 
sionally endorse  it.  On  the  whole,  modern 
science  is  nothing  if  not  catholic  in  its 
generosity.  '  To  promote  the  increase  of 
natural  knowledge  and  to  forward  the  ap- 
plication of  scientific  methods  of  investiga- 
tion to  all  the  problems  of  life '  was  the 
avowed  purpose  of  the  greatest  of  the  phi- 
losophers of  the  Victorian  era. 

There  are  those  who  are  full  of  a  similar 
good  will,  but  they  fail  in  giving  effect  to  it 
because  they  are  unable  to  use  language 
which  can  be  widely  understood.  In  its 
very  infancy  geology  was  nearly  choked 
with  big  words,  for  Lyell,  the  father  of 
modern  geology,  said,  seventy  years  ago, 
that  the  study  of  it  was  '  very  easy,  when 
put  into  plainer  language  than  scientific 
writers  choose  often  unnecessarily  to  em- 
ploy/ At  this  day  even  the  publications 
of  the  Geological  Surveys  of  the  United 
States  and  the  Australian  colonies,  for  ex- 
ample, are  occasionally  restricted  in  use- 
fulness by  erring  in  this  respect,  and  as  I 
yield  to  none  in  my  appreciation  of  the 
splendid  service  done  to  geology  and  to 
mining  by  these  surveys,  I  trust  my  criti- 
cism will  be  accepted  in  the  thoroughly 
friendly  spirit  with  which  it  is  offered.  It 


12 

seems  to  me  that  one  might  almost  say 
that  certain  of  these  extremely  valuable 
publications  are  "  '  badly  '  prepared  be- 
cause they  seem  to  overlook  the  fact  that 
they  are,  of  course,  intended  to  aid  the 
mining  community  in  the  first  place  and 
the  public,  whether  lay  or  scientific,  only 
secondarily.  From  a  wide  experience 
among  those  engaged  in  mining  I  can 
testify  that  a  large  part  of  the  literature 
thus  prepared  is  useless  to  them  and  that 
no  one  regrets  it  more  deeply  than  they, 
because  there  is  a  marked  tendency  among 
this  class  of  workers  to  appreciate  the 
assistance  which  science  can  give.  Take, 
for  example,  a  sentence  like  the  following, 
extracted  from  one  of  the  recent  reports  of 
the  U.  S.  Geological  Survey.  "The  ore 
forms  a  series  of  imbricating  lenses,  or  a 
stringer  lead,  in  the  slates,  the  quartz  con- 
forming as  a  rule  to  the  carunculated 
schistose  structures,  though  occasionally 
breaking  across  laminae,  and  sometimes  the 
slate  is  so  broken  as  to  form  a  reticulated 
deposit/'  This  was  written  by  one  of  our 
foremost  geologists  and,  when  translated, 
the  sentence  is  found  to  convey  a  useful 
fact,  but  is  it  likely  to  be  clear  to  anyone 
but  a  traveling  dictionary?  A  thoroughly 
literary  man  might  know  the  exact  mean- 
ing of  the  two  or  three  very  unusual 
words  which  are  employed  in  this  state- 
ment, but  the  question  is,  will  it  be  of  any 
use  whatever  even  to  a  fairly  educated 
miner,  or  be  understood  by  those  who  pay 
for  the  preparation  of  such  literature, 
namely,  the  taxpayers?  An  example  of 
another  kind  is  afforded  by  a  Tasmani^n 
geologist  who  recently  described  certain 
ores  as  due  to  '  the  effects  of  a  reduction  in 
temperature  of  the  hitherto  liquefied  hy- 


13 

droplutonic  solutions,  and  their  conse- 
quent regular  precipitation.'  These  solu- 
tions, it  is  further  stated,  presumably 'for 
the  guidance  of  those  who  wield  the  pick, 
'  ascended  in  the  form  of  metallic  super- 
heated vapors  which  combined  eventually 
with  ebullient  steam  to  form  other  aque- 
ous solutions,  causing  geyser-like  discharges 
at  the  surface,  aided  by  subterranean  and 
irrepressible  pressure/  At  the  same  time 
certain  *  dynamical  forces '  were  very  busy 
indeed  and  'eventuated  in  the  opening  of 
fissures' — of  which  one  can  only  regret 
that  they  did  not  swallow  up  the  author 
as  Nathan  and  Abiram  were  once  engulfed 
in  the  sight  of  all  Israel. 

It  will  be  well  to  contrast  these  two  ex- 
amples of  exuberant  verbosity  because  the 
first  befogs  the  statement  of  a  scientific 
observation  of  value,  made  by  an  able  man, 
while  the  second  cloaks  the  ignorance  of  a 
charlatan,  who  masquerades  his  nonsense 
in  the  trappings  of  wisdom.  Here  you 
have  an  illustration  of  the  harmfulness  of 
this  kind  of  language,  which  obscures 
truth  and  falseness  alike,  to  the  degrada- 
tion of  science  and  the  total  confusion  of 
those  of  the  unlearned  who  are  searching 
after  information. 

Let  the  writer  on  scientific  matters  learn 
the  derivation  of  the  words  he  uses  and 
then  translate  them  literally  into  English 
before  he  uses  them,  and  thereby  avoid  the 
unconscious  talking  of  nonsense.  If  he 
knows  not  the  exact  meaning  of  the  terms 
which  offer  themselves  to  his  pen,  let  him 
avoid  them  and  trust  to  the  honest  aid  of 
his  own  language.  '  Great  part  of  the  sup- 
posed scientific  knowledge  of  the  day  is 
simply  bad  English,  and  vanishes  the 
moment  you  translate  it,'  says  Ruskin. 


14 

The  examples  already  given  illustrate  this. 
'  Every  Englishman  has,  in  his  native 
tongue,  an  almost  perfect  instrument  of 
literary  expression,'  so  says  Huxley,  and 
he  illustrated  his  own  saying.  Huxley  and 
Ruskin  were  wide  apart  in  many  things 
and  yet  they  agreed  in  this.  Ruskin 
proved  abundantly  that  the  language  of 
Shakespeare  and  the  Bible  can  be  used  as 
a  weapon  of  expression  keen  as  a  Damascus 
saber  when  it  is  freed  from  the  rust  of 
classic  importations,  which  make  it  clumsy 
as  a  crowbar. 

There  is  yet  another  reason  against  the 
excessive  use  of  Greek-English  words,  in 
particular.  Greece  is  not  a  remnant  of  ex- 
tinct geography,  but  an  existing  land  with 
a  very  active  people  and  a  living  language. 
The  terms  which  paleontology  has  bor- 
rowed from  the  Greek  may  be  returned  by 
the  Greeks  to  us.  And,  as  Ruskin  points 
out,  ' '  What  you,  in  compliment  to  Greece 
call  a  '  Dinotherium, '  Greece,  in  compli- 
ment to  you,  must  call  a  '  Nasty-beastium, ' 
and  you  know  the  interchange  of  compli- 
ments can't  last  long." 

In  all  seriousness,  however,  is  it  too 
much  to  ask  that  such  technical  terms  as 
are  considered  essential  shall  not  be  used 
carelessly,  and  that  in  publications  in- 
tended for  an  untechnical  public,  as  are 
most  government  reports,  an  effort  be 
made  to  avoid  them  and,  where  unavoid- 
able, those  which  are  least  likely  to  be  un- 
derstood shall  be  translated  in  footnotes. 
Even  as  regards  the  transactions  of  scien- 
tific societies,  I  believe  that  those  of  us 
who  are  active  members  have  little  to  lose 
and  much  to  gain  by  confining  the  use 
of  our  clumsy  terminology  to  cover  ideas 
which  we  cannot  otherwise  express.  By 


15 

doing  so  we  shall  contribute,  I  earnestly 
believe,  to  that  advancement  of  science 
which  we  all  have  at  heart. 

The  words  which,  at  first,  are  the  ex- 
clusive privilege  of  the  specialist,  gradually 
extend  into  wider  use,  following  in  the 
wake  of  that  diffusion  of  scientific  knowl- 
edge which  is  one  of  the  objects  of  this 
Association.  We  believe  that  to  get  along- 
side facts,  to  apply  the  best  knowledge 
available,  to  seek  truth  for  its  own  sake,  is 
as  essential  to  the  well-being  of  the  in- 
dividual life  as  it  is  to  the  success  of  a 
machine  shop,  and  as  beneficial  to  the  com- 
munity as  it  is  to  a  smelting  works. 

In  furtherance  of  this  principle  we  must 
remember  that  language  in  relation  to 
ideas  is  a  solvent,  the  purity  and  clearness 
of  which  affect  that  which  it  bears  in  solu- 
tion. Whewell,  in  '  The  Philosophy  of  the 
Inductive  Sciences, 'has  expressed  this  view 
of  the  matter  with  noble  eloquence.  '  Lan- 
guage, '  he  said,  l  is  often  called  an  instru- 
ment of  thought,  but  it  is  also  the  nutri- 
ment of  thought;  or  rather,  it  is  the 
atmosphere  in  which  thought  lives;  a 
medium  essential  to  the  activity  of  our 
speculative  powers,  although  invisible  and 
imperceptible  in  its  operation,  and  an  ele- 
ment modifying,  by  its  qualities  and 
changes,  the  growth  and  complexion  of  the 
faculties  which  it  feeds.' 

In  considering  the  subject  from  this 
standpoint,  there  is  borne  in  upon  the 
mind  a  suggestion  which  carries  our 
thought  far  beyond  the  confines  of  the  mat- 
ter under  discussion.  Such  power  of 
speech  as  man  possesses  is  a  faculty  which 
appears  to  divide  him  from  all  other  liv- 
ing things,  while  at  the  same  time  the  im- 
perfection of  it  weighs  him  down  con- 


16 

tinually  with  the  sense  of  an  essential 
frailty.  To  be  able  to  express  oneself  per- 
fectly would  be  divine,  to  be  unable  to 
make  oneself  understood  is  human.  In 
'Man's  Place  in  Nature/  Huxley  points 
out  that  the  endowment  of  intelligible 
speech  separates  man  from  the  brutes 
which  are  most  like  him,  namely,  the  an- 
thropoid apes,  whom  he  otherwise  resem- 
bles closely  in  substance  and  in  structure. 
This  endowment  enables  him  to  transmit 
the  experience  which  in  other  animals  is 
lost  with  each  individual  life;  it  has  en- 
abled him  to  organize  his  knowledge  and 
to  hand  it  down  to  his  descendants,  first  by 
word  of  mouth  and  then  by  written  words. 
If  the  experience  thus  recorded  were  prop- 
erly utilized,  instead  of  being  largely  disre- 
garded, then  man's  advancement  in  knowl- 
edge and  conduct  would  enable  him  to 
emphasize,  much  more  than  it  is  permitted 
him  at  present,  his  superiority  over  the 
dumb  brutes.  Considered  from  this  stand- 
point language  is  a  factor  in  the  evolution 
of  the  race  and  an  instrument  which  works 
for  ethical  progress.  It  is  a  gift  most  truly 
divine  which  should  be  cherished  as  the 
ladder  which  has  permitted  of  an  ascent 
from  the  most  humble  beginnings  and  leads 
to  the  heights  of  a  loftier  destiny,  when 
man,  ceasing  to  stammer  forth  in  accents 
which  are  but  the  halting  expression  of 
swift  thought,  shall  photograph  his  mind 
in  the  fulness  of  speech,  and,  neither  with- 
holding what  he  wants  to  say  nor  saying 
what  he  wants  to  withhold,  shall  be  linked 
to  his  fellow  by  the  completeness  of  a  per- 
fect communion  of  ideas. 
DENVEB.  T.  A.  RlCKAED. 


"  The  Minerals  which  accompany  Gold,  and  their  bearing 
upon  the  Richness  of  Ore  Deposits." 

By  T.  A.  RICKARD,  M.Inst.  M.M. 

IN  the  general  advance  of  knowledge  anatomy  has  distanced 
medicine.  The  surgeon  works  with  confident  skill  while  the 
diagnosis  of  the  physician  is  yet  a  faltering  guess.  It  is  thus  in 
our  own  profession.  The  structure  of  the  rocky  envelope  of  the 
earth  has  been  in  many  localities  so  carefully  deciphered  that  the 
mining  engineer  can  unravel  the  geology  of  an  ore  deposit  with  a 
saccess  to  which  the  mines  of  Leadville,  Bendigo  and  Gympie 
bear  ungrudging  testimony.  When,  however,  he  endeavours  to 
ascertain  the  causes  which  have  determined  the  presence  of  gold 
at  one  spot  and  its  absence  at  another  he  hesitates,  and,  saturated 
with  the  brutal  experience  of  widely  separated  regions,  he  con- 
fesses that  it  is  a  phenomenon  yet  to  be  explained. 

The  working  of  gold  mines  in  different  countries  has  yielded  an 
accumulation  of  scattered  evidence  which  needs  only  scant  examina- 
tion to  emphasise  how  incomplete  and  contradictory  it  is.  The 
absence  of  accurate  knowledge  on  this  subject  has  encouraged  the 
growth  of  attractive  fallacies,  in  the  combating  of  which  the  whole 
matter  often  comes  up  for  informal  discussion  wherever  mining 
men  congregate.  During  recent  journeyings  over  the  goldfields 
of  West  Australia,  I  found  that  many  an  old  fallacy  had  sprung 
again  into  vigorous  life  amid  the  congenial  atmosphere  of  a  com- 
munity over  which  the  windy  breath  of  a  boom  had  but  lately 
passed. 

It  may  seem  a  thankless  task  to  oppose  those  plausible  theories, 
which  become  rampant  only  when  facts  are  scarce,  yet  I  am 
convinced  that  in  the  search  after  truth  the  first  step  must  be  to 

B 


sift  the  little  that  \ve  really  do  know  from  the  much  that  we  think 
we  know  ;  the  first  is  science,  the  second  is  popular  knowledge. 
The  old  industry  of  mining  was  formerly  guided  by  the  venerable 
rule  of  thumb,  and  would  forever  have  remained  but  a  blind  sort 
of  groping  in  the  dark  had  it  not  obtained  the  willing  aid  of  the 
younger  science  of  geology. 

The  immediate  problem  to  which  my  most  recent  experience 
has  called  attention  may  be  summarised  thus  : — In  examining  a 
lode  only  incompletely  developed  and  in  a  new  country,  what  is 
the  evidence  on  which  a  correct  estimate  of  the  prospective  value 
of  the  mine  may  best  be  based  ?  The  two  most  common  answers 
would  be  a  plain  denial  of  any  man's  ability  to  see  further  into 
the  ground  than  the  point  of  his  pick,  and  against  this  obvious 
surrender  would  come  the  reply  that  the  best  indication  would  be 
found  in  the  presence  of  particular  minerals  in  association  with 
the  gold. 

It  is  this  question  of  indicative  minerals  which  I  purpose  dis- 
cussing. The  experience  of  certain  mining  districts  has  gone  to 
prove  that  gold  is  notably  accompanied  by  particular  minerals, 
and  this  to  such  an  extent  that  they  are  considered  to  assure  the 
richness  of  an  ore  in  which  the  gold  itself  cannot  visibly  be 
discerned.  These  "  indicative  minerals,"  as  they  may  be  termed, 
are  not  the  same  in  every  locality.  A  few  examples,  such  as 
have  come  within  my  own  experience,  may  be  quoted.  Every 
mining  engineer  can  add  to  the  list. 

In  Boulder  county,  Colorado,  roscoelite  (a  vanadium  mica)  is 
closely  associated  with  the  tellurides  of  gold  (calaverite  and 
sylvanite).  This  fact  is  rendered  of  additional  interest  because  the 
same  rare  mineral  has  been  recognised  by  me  in  the  telluride  ores 
of  Kalgoorlie,  in  West  Australia.*  At  San  Andreas,  in  California, 
uranium  ochre  (the  yellow  oxide  of  uranium)  is  found  to  distin- 
guish the  pockets  of  specimen  gold  ore  to  such  an  extent  as  to 
serve  as  a  guide  in  prospecting.  In  several  parts  of  Arizona,  in 
Yuma,  Yavapai  and  Final  counties,  especially  the  last,  vanadinite 
and  descloizite  (both  vanadates  of  lead)  characterise  ores  rich  in 
gold  and  silver.  Wulfeiiite  (the  molybdate  of  lead)  often  accom- 
panies the  vanadium  minerals,  and  has  been  noticed  in  the  ores  of 
two  celebrated  lodes,  the  Comstock  in  Nevada  and  the  Vulture 
in  Arizona.  The  association  of  gold  with  these  lead  ores  is 
notable,  because  the  particular  minerals  mentioned  are  all  of 
great  beauty  and  delicacy.  The  same  may  be  said  of  crocoite 

*  Eoscoelite  also  occurs  generously  in  the  veins  of  the  district  (El  Dorado) 
where  gold  was  first  discovered  in  California. 


(the  chromate  of  lead),  which  characterises  several  gold  veins  in 
the  North  Coolgardie  goldfield,  especially  at  Menzies.*  The 
more  common  sulphide,  galena,  is  also  an  accessory  mineral  in  the 
richest  mines  at  Menzies,  and  accompanies  coarse  native  gold.  At 
Niagara,  Pinyalline,  and  Wagiemoola,  three  widely  separated 
localities  in  West  Australia,  I  found  gold  closely  associated  with 
tourmaline  in  the  form  of  acicular  crystals  in  contact  with  coarse 
pold,  and  also  in  a  condition  of  minute  diffusion  forming  dark 
blotches  in  the  white  quartz.  The  gold  ores  of  the  Mysore  in 
India  carry  tourmaline. 

Instances  might  be  multiplied,  but  it  would  be  to  no  purpose. 
Those  already  cited  will  serve  as  a  sufficient  text  for  the  discus- 
sion of  the  subject. 

Such  occurrences  as  these  would  seem  at  first  sight  to  afford 
a  much  needed  aid  to  the  explorer.  It  is  unfortunately  easy 
to  prove  that  as  evidence  they,  and  any  number  more  of  them, 
are  of  very  uncertain  value  in  a  new  mining  territory,  because 
they  are  contradicted  by  similar  testimony  of  a  negative  kind, 
which  compels  us  to  regard  them  as  mere  coincidences.  Take  the 
case  of  zinc  blende.  One  locality  was  quoted  where  this  mineral 
is  a  sure  sign  of  a  generous  amount  of  gold  and  silver  in  the  ore. 
The  Morgan  Mine,  in  Wales,  affords,  I  understand,  corroborative 
testimony.  At  the  East  Murchison  Mine,  in  West  Australia,  this 
mineral  has  been  found  to  be  an  almost  unerring  guide  in  separat- 
ing rich  from  poor  ore.  But  in  Arizona  it  is  a  common  experience 
that  the  impoverishment  of  lodes  in  depth,  when  it  does  occur,  is 
concomitant  with  an  increasing  percentage  of  zinc.  Other  regions 
echo  this  unpleasant  fact.  Broken  Hill  knows  it.  Similarly,  there 
is  the  beautiful  mineral  fluorite  or  fluorspar.  The  association  of 
fluorite  with  the  tellurides  of  gold  was  early  recognised  in  both 
the  Boulder  and  Cripple  Creek  districts  of  Colorado,  and  the 
purple  tint  imparted  by  this  mineral  was  speedily  bailed  as  a 
distinction  peculiar  to  rich  veins.  Later  experience,  notably  in 
Park  County,  has  proved  that  poor  ores  are  favoured  with  fluorite 
no  less  than  the  bonanzas.  1  have  mentioned  a  locality  where 
rhodochrosite  is  esteemed  a  favourable  mineral.  But  while  it  is 
thus  characteristic  of  rich  ore  at  Rico,  in  Colorado  it  is  a  negligi- 
ble factor  in  certain  lodes  at  Butte  City,  Montana.  Again, 
consider  calcite.  When  it  is  seen  amid  the  gold  bearing  quartz  of 
California  it  is  recognised  with  regret,  because  it  so  often  means  a 
falling  off  in  values,  while  at  Kalgoorlie  the  same  mineral  charac- 

*  Dana   mentions   that   crocoite   is   associated  with  gold  in  the   quartz  of 
Kiznhi  Tagilsk  in  the  Urals. 

B   2 


terises  ores  rich  in  calaverite  (the  telluride  of  gold),  and  at  Rhuda 
in  Transylvania,  a  very  valuable  gold  vein  has  been  worked  whose 
matrix  was  essentially  calcite. 

We  are  all  familiar  with  mines  in  which  iror  pyrites  is  so 
intimately  associated  with  the  gold  that  a  lessening  of  the  one 
means  a  diminution  in  the  other,  but  there  are  also  cases  where 
an  excessive  percentage  of  pyrites  coincides  with  impoverishment. 
Moreover,  there  are  lodes  in  which  the  coarse  cubes  of  pyrites  are 
less  favourable  to  the  presence  of  gold  than  the  finely  crystalline 
variety,  but  there  are  also  those  in  which  the  reverse  is  true. 
Much  in  the  same  way,  there  used  to  be  an  idea  that  coarse  cubical 
galena  was  less  silver-bearing  than  the  fine  grained  kind,  but  this 
as  a  generalisation  has  long  since  been  exploded.  Thus,  therefore, 
it  requires  but  little  sifting  of  this  sort  of  evidence  to  emphasise 
its  contradictory  character. 

The  rich  lodes  of  the  same  district  frequently  differ  widely  in 
their  mineralisation.*  Poor  veins  often  carry  the  ores  considered 
characteristic  of  the  rich  ones.  The  neglect  of  the  former  causes 
this  fact  to  be  overlooked.  "When  the  field  of  comparison  is 
enlarged  from  mines  to  whole  districts  the  divergence  of  evidence 
becomes  tenfold  emphasised. 

In  matters  like  these  the  experience  of  each  mining  engineer 
is  a  personal  equation  by  which  every  theory  must  be  eventually 
tested.  Out  of  the  whole  sad  wreck  of  glittering  generalisations 
on  this  particular  subject,  only  one  or  two  have  survived  my  own 
particular  trial  of  them,  and  even  they,  I  fear,  await  the  destruc- 
tive testimony  which  may  at  any  moment  be  found  in  the  develop- 
ment of  new  mining  regions.  When  gold  occurs  in  pyrrhotite 
ores  it  has  been  as  yet  invariably  proved  to  be  in  immediate  asso- 
ciation with  a  small,  often  overlooked,  percentage  of  copper 
pyrites.  The  testimony  of  Montana,  Colorado,  and  British 
Columbia  is  at  one  in  this  deduction.  Again,  while  many  veins 
carrying  coarse  gold  encased  in  white  quartz  persist  to  great 
depths,  and  in  this  respect  Bendigo  does  especially  set  at  naught 
the  dictum  of  American  experience,  nevertheless  I  have  not  known 
gold  quartz  to  be  persistent  when  wholly  barren  of  the  sulphides 
of  the  baser  metals,  while,  on  the  other  hand,  I  do  remember  in- 
numerable examples  of  ore  quite  destitute  of  pyrites,  galena,  and 
blende  which  proved  particularly  short  lived.  I  might  venture 

*  This  word  is  not  of  vulgar  coinage.  It  comes  through  the  French,  who 
use  it  as  we  do,  to  express  the  fact  that  a  rock  carries  minerals  of  economic 
value,  that  is,  ore.  "  Mineralise  "  is  the  equivalent  of  "  mineralised,"  and  is 
related  rather  to  the  word  "  mineral"  (ore)  than  to  "  mineral." 


one  other.  There  is  no  better  indirect  evidence  of  the  size  of  a 
body  of  gold  ore  than  uniformity  in  the  distribution  of  the  gold. 
A  patchy  occurrence  is  less  likely  than  homogeneity  to  indicate 
continuity  or  size;  samples  which  vary  between  narrow  limits  are 
more  encouraging  than  those  which  swing  between  wide  extremes 
of  richness  and  poverty.  It  is  with  a  desire  to  avoid  a  merely 
destructive  attitude  that  I  have  dared  to  offer  these  three  obser- 
vations. 

While  therefore  the  evidence  in  support  of  the  value  of  the 
supposed  indicative  minerals  is,  as  we  have  seen,  of  a  very  contra- 
dictory nature,  it  also  has  another  feature  which  must  not  be 

overlooked.     At  its  best,  the  aid  of  these  minerals  would  be  delu- 

«• 
sive,  because,  even  if  it  proved  the  invariable  association  of  gold 
with  particular  minerals,  it  could  not  predicate  the  actual  amount 
of  that  gold.  That  a  lode  should  carry  gold  is  quite  insufficient 
to  the  mining  engineer,  whose  operations  for  its  profitable  extrac- 
tion require  that  it  should  be  there  in  paying  quantity.  This  is 
the  difference  between  science  and  business.  The  union  of  the 
two  creates  an  industry.  One  might  discuss  in  a  learned  and 
entertaining  manner,  as  Stelzner  has  done,  the  suggestiveness  of 
the  association  of  gold  with  such  a  compound  as  the  silicate  of 
boron  and  aluminium  (tourmaline),  because  it  indicates  a  deep- 
seated  origin.  The  presence  in  notable  quantity  of  the  fluoride  of 
calcium  (fluorspar)  might  prompt  speculations  of  a  vapourous  and 
corroding  kind.  But  the  proof  of  gold  having  either  a  profound 
or  a  gaseous  origin,  were  it  attained  by  the  geologist  or  chemist, 
would  not  permit  the  mining  engineer  to  infer  that  the  gold  per- 
sists in  paying  quantity  to  any  particular  depth.  An  ore  which 
carries  2  dwt.  per  ton  in  a  region  where  the  conditions  are  such 
as  to  require  the  equivalent  of  15  dwt.  to  be  expended  in  the 
extraction  and  reduction  of  a  ton,  is  to  all  practical  intent  as  value- 
less as  one  which  is  wholly  barren. 

The  question  of  indicative  minerals  bears  many  points  of  resem- 
blance to  that  of  the  plants  which  have  been  observed  to  distin- 
guish the  soil  enriched  by  particular  ores.  The  Viola  Intea  was 
supposed  to  be  peculiar  to  the  soil  covering  the  zinc  deposits  of 
Westphalia,  and  was  subsequently  recognised  growing  on  the  out- 
crop of  the  zinc  ores  of  the  Horn  Silver  Mine  in  Utah.  It  became 
known  as  the  "  zinc  plant."  Similarly  there  is  a  so-called  "  lead 
plant,"  the  Amorpha  canescens,  which  characterises  the  lead  deposits 
of  Michigan,  Wisconsin,  and  Illinois.  These  plants  are  local 
varieties  rather  than  a  distinct  species,  their  colour  being  affected 
by  their  absorption  of  the  particular  metallic  ingredient  in  the 


soil.*  Their  occurrence  has  long  ceased  to  have  anything  more 
than  academic  interest. 

If  then  we  cannot  accept  the  belief  that  certain  minerals  are 
indicative  of  the  plentiful  occurrence  of  gold,  what  shall  be  said 
for  the  idea  that  they  give  an  assurance  of  persistence  in  depth  ? 
Every  one  has  read  serious  statements  to  the  effect  that  this  or 
that  mine  was  of  undoubted  value  because  its  ores  contained  par- 
ticular minerals,  the  presence  of  which  promised  that  the  vein 
would  increase  in  richness  in  depth.  In  young  mining  regions 
such  ideas  find  a  fertile  soil.  In  West  Australia  the  finding  of 
tellurides  in  an  ore  is  now  generally  considered  to  permit  of  the 
inference  that  the  lode  will  go  down  to  a  great  depth.  The  early 
discoveries  of  extraordinary  pockets  of  native  gold  in  veins  of 
white  quartz,  such  as  made  the  Londonderry  famous,  proved 
sporadic  and  bunchy  to  a  distressing  degree.  When,  therefore, 
the  telluride  ores  of  Kalgoorlie  became  recognised,  and  were  found 
to  occur  in  bodies  of  magnificent  size  and  very  satisfactory  per- 
sistence, the  conclusion  was  jumped  at  that  if  tellurides  were  only 
present  in  an  ore,  continuity  in  depth  became  thereby  guaranteed. 
Post  hoc,  ergo  propter  hoc. 

In  these  matters  a  very  small  portion  of  ascertained  truth  is 
swamped  amid  a  mass  of  supposition  quite  unworthy  of  the  name 
of  theory.  A  theory  embodies  an  underlying  principle  of  universal 
application.  The  idea  which  to-day  dominates  the  mining  of  Wes- 
tralia  is  a  vain  imagining,  delusive  as  a  promoter's  dream. 

Those  who  are  acquainted  with  the  history  of  the  mining  of 
tellurides  need  not  be  told  how  ill  founded  is  the  statement  that 
these  particular  minerals  characterise  lodes  of  peculiar  perma- 
nence. The  combinations  of  tellurium  with  gold  and  silver  have 
proved  of  notable  commercial  importance  in  three  mining  regions, 
namely,  Transylvania,  Colorado,  and  West  Australia.  There  are 
other  districts  where  the  mining  of  them  is  an  incident  in  the 
working  of  ordinary  gold  ores.  Such  is  the  case  in  certain  locali- 
ties in  California,  South  Dakota,  and  the  North  Island  of  New 
Zealand.  In  none  of  these,  however,  have  they  been  indicative 
of  any  special  persistence  in  the  richness  of  the  veins,  and  their 
occurrence  has  been  merely  an  added  obstacle  to  the  successful 
extraction  of  the  gold. 

It  was  in  1802  that  Klaproth  discovered  the  presence  of  a  new 
element,  tellurium,  in  the  ores  of  Zalathna,  and  so  led  to  the 
recognition  of  a  large  number  of  the  compounds  of  that  metal 

*  See  "  Indicative  Plants,"  by  E.  W.  Kajrnond,  Trans.  Amer.  last,  of  M.E., 
vol.  xv,  p.  644. 


with  gold  and  silver.  Zalathua,  Nagyag,  and  Verospatak  were 
gold  mining  centres  when  Transylvania  was  the  Roman  province 
of  Dacia  and  was  ruled  by  Trajan.  The  very  complex  ores  of  these 
districts  have  been  a  puzzle  to  the  metallurgists  of  many  genera- 
tions. The  veins  penetrate  young  volcanic  rocks  (andesites)  and 
Tertiary  limestones,  sandstones,  and  conglomerates.  This  very 
ancient  mining  country  exhibits  to-day  a  very  forceful  example  of 
impoverishment  in  depth,  while  the  refractory  character  of  the 
ores  has  tried  the  resources  of  the  smelting  establishments  of 
Schemnitz,  Zalathna,  and  Freiberg. 

In  Colorado  the  tellurides  were  recognised  as  early  as  1874  in 
Boulder  county,  more  especially  at  the  mines  of  Magnolia,  Salina, 
and  Sunshine.  An  experience  of  nearly  twenty-five  years  has  proved 
to  the  miners  of  that  county  that  these  ores  occur  there  in  compara- 
tively small  bodies  of  remarkable  richness  but  of  very  irregular 
and  uncertain  behaviour.  In  two  other  districts  of  the  same  State, 
namely,  in  Hinsdale  county  and  amid  the  La  Plata  mountains, 
valuable  mines,  carrying  ores  rich  in  the  tellurides  of  gold  and 
silver,  have  been  worked  during  the  past  ten  years,  but  their 
record  corroborates  that  of  Boulder.  There  remains  the  more 
important  goldfield  of  Cripple  Creek,  where  veins  penetrating  a 
remarkable  complex  of  volcanic  rocks  have  proved  so  persistently 
rich  to  a  depth  now  approaching  one  thousand  feet,  that  they  have 
obliterated  the  reputation  which  this  class  of  ore  won  in  the  three 
older  parts  of  the  same  State. 

In  West  Australia  tellurides  are  being  mined  in  three  localities 
— Redhill,  Bardoc,  Kalgoorlie — and  the  wonderful  development  of 
the  last  has  given  a  new  impulse  to  the  whole  industry  of  the  colony. 

Thus,  one  hears  much  of  Cripple  Creek,  and,  lately,  of  Kal- 
goorlie. In  both  districts  very  rioh  lodes,  characterised  by  telluride 
ores,  have  been  opened  up,  with  results  so  eloquent  as  to  silence 
the  story  of  the  more  numerous  localities  where  these  particular 
minerals  have  been  only  a  metallurgical  obstacle  associated  with 
ore  bodies  of  no  satisfactory  continuity.  As  a  consequence, 
investors  are  prepared  to  swallow  the  rhetorical  confectionery  of 
an  irresponsible  press,  and  to  believe  that  a  new  era  has  dawned 
for  any  neglected  region  in  which  these  tellurides  are  now  for  the 
first  time  recognised.  Believe  me,  the  compounds  of  tellurium 
are  far  more  widely  dispersed  in  gold  ores  than  is  generally  sup- 
posed. I  have  detected  them  in  several  mines  when  a  low  extrac- 
tion in  the  stamp  mill  suggested  an  unusual  difficulty  in  the  ore, 
and  it  is  certain  that  during  the  next  few  years  the  greater 
familiarity  with  these  minerals  will  lead  to  their  recognition  in 


8 

so  many  unsuspected  localities,  that  they  will  cease  to  be  a 
mineral ogical  curiosity.* 

The  idea,  now  very  prevalent,  that  at  Kalgoorlie  especially  the 
presence  of  tellurides  guarantees  persistent  richness  is  contradicted 
by  several  facts,  the  most  notorious  of  which  should  be  the  fact 
that  the  very  mine  in  which  they  were  first  recognised  (by  Mr.  J. 
C.  Moulden,  in  May,  1896),  and  subsequently  acclaimed  by  the 
local  press  as  heralding  sure  prosperity,  has  proved  unprofitable ; 
indeed,  the  particular  ore-body  in  which  the  first  telluride  was 
seen  has  been  demonstrated  by  later  development  to  be  an  isolated 
patch  leading  to  nothing  of  any  moment.  Moreover,  the  lodes  at 
Kalgoorlie  vary  in  the  amount  of  tellurides  which  they  carry 
without  any  proportionate  difference  in  their  richness.  The 
gold  occurs  not  only  in  chemical  combination  with  tellurium,  but 
also  in  its  ordinary  native  condition.  Further,  tellurides  occur 
which  do  not  contain  gold.  The  so-called  "  black  tellurium"  of 
certain  mines  is  the  rare  telluride  of  mercury,  called  "  coloradoite," 
from  the  locality  of  its  first  discovery.  Native  tellurium  also 
exists.  Again,  some  of  the  veins  even  below  the  zone  of  oxidation 
are  so  free  from  tellurium  as  not  to  differ  from  ordinary  gold- 
bearing  reefs.  Yet  there  is  no  reason  to  suppose  that  these  are 
less  rich  or  less  persistent  than  those  which  are  characterised  by 
a  notable  percentage  of  tellurides. 

It  is  not  too  much  to  say,  therefore,  that  the  observations 
gathered  from  the  working  of  telluride  ores  in  various  parts  of 
the  world  refute  the  idea  that  their  occurrence  has  any  particular 
bearing  on  the  question  of  persistence  in  depth  ;  while,  on  the 
other  hand,  experience  has  frequently  demonstrated  that  their 
presence  is  an  important  and  objectionable  factor  from  a  metal- 
lurgical standpoint,  because  it  increases  the  cost  of  gold  extraction. 

Thus  we  are  brought  to  face  the  general  question  of  the  enrich- 
ment of  ores  in  depth.  It  is,  however,  outside  the  scope  of  this 
contribution.  As  a  far-reaching  fallacy,  persisting  in  spite  of  the 
accumulated  experience  of  many  mining  regions,  it  possesses  a 
pestilent  vitality,  which  must  at  times  astonish  those  who  from 
the  actual  direction  of  mining  operations  have  seen  so  much 
evidence  to  the  contrary.  I  am  referring  now  to  gold  mines  only, 

*  The  sulphide  ore  of  Mount  Morgan,  Queensland,  carries  tellurides.  The 
fict  was  recently  determined  by  Mr.  E.  S.  Simpson,  G-overnment  Assayer  for 
West  Australia.  How  much  of  the  early  trouble  in  the  treatment  of  the 
oxidised  ores  is  explained  by  this  discovery  ?  It  also  recalls  to  me  the 
resemblance  between  the  dull  brown  gold  of  some  of  the  Mount  Morgan  ore 
and  that  of  the  first  discoveries  at  Cripple  Creek  in  1892. 


because  the  facts  relating  to  baser  metals,  which  by  oxidation 
become  soluble,  differ  in  detail.  Gold  and  tin  are  in  this  respect 
unlike  copper  and  silver.  While,  therefore,  I  do  not  wish  on  this 
occasion  to  reopen  the  whole  subject,  I  cannot  forbear  referring 
to  the  question  as  it  has  come  up  for  discussion  in  West  Australia, 
where  I  have  lately  been. 

In  that  country  the  assertion  is  made  with  tiresome  iteration 
that  veins  become  richer  below  the  water  level,  because  in  the 
oxidised  zone  the  ore  has  been  impoverished  by  the  leaching  out 
of  the  gold.  It  is  also  held  by  many  who  pose  as  having  authority 
and  not  as  the  scribes,  that  if  the  outcrop  give  evidence  of  notable 
mineralisation  it  is  reasonable  to  expect  almost  barren  quartz  to 
become  valuable  when  the  sulphides  are  reached  in  the  ordinary 
course  of  deeper  mining.  If  these  pleasant  doctrines  are  ques- 
tioned, you  are  bidden  to  go  to  Kalgoorlie,  where,  so  they  say, 
you  will  be  forced  by  the  evidence  there  obtainable  to  admit  the 
fact  that  lodes  which  now  attract  the  attention  of  the  financial 
world,  were  too  poor  to  meet  expenses  until  the  mine  workings 
penetrated  into  the  unoxidized  ore.  Indeed,  at  Kalgoorlie  especi- 
ally this  idea  has  a  strong  foothold,  especially  among  stock- 
jobbers. 

The  matter  seemed  to  me  to  be  one  of  great  interest.  If  the 
facts  really  did  indicate  a  general  enrichment  of  the  veins  as  they 
approached  the  drainage  level  of  the  district,  which  is  also  the 
water  level  of  the  mines,  then  Kalgoorlie  offered  a  striking  excep- 
tion to  the  experience  of  other  goldfields.  If,  moreover,  a  satis- 
factory theory  were  forthcoming  to  account  for  these  unusual 
facts,  then  the  uncertain  chemistry  of  ore  occurrence  would 
receive  invaluable  aid.  But  the  prettily  coloured  bubble  was 
dissipated  as  soon  as  an  earnest  investigation  was  commenced. 
The  history  of  the  development  of  the  lodes,  and  a  few  quiet  con- 
versations with  the  able  men  who  have  come  from  elsewhere  to 
direct  the  big  mines,  were  sufficient  to  stamp  this  as  another 
resurrection  of  a  fallacy  that  was  old  before  the  Phoenicians  came 
to  Cornwall. 

To  say  that  mines  get  richer  in  depth  is,  in  such  a  region  as 
West  Australia,  a  cruel  cynicism.  If  anyone  is  inclined  to  believe 
it,  let  him  wander  over  the  desert,  and  count  the  idle  stamp  mills 
which  lie  rusting  in  the  sweltering  sun,  and  the  long  succession  of 
abandoned  shafts  which  now  serve  only  to  water  the  passing 
camel  train.  By  mere  repetition  of  an  untruth  you  may  effect 
persuasion,  but  you  do  not  alter  the  falsity  of  it. 

If  you  omit  the  manifest  failures  and  turn  to  the  production  of 

B  3 


10 

the  more  successful  mines  in  the  Menzies,  Murchison,  Cool- 
gardie,  and  Norseman  goldfields,  you  will  still  find  that  it  is  a 
work  of  supererogation  to  attempt  a  serions  discussion  of  the 
statement  that  the  veins  have  improved  in  depth.  Incomplete  as 
the  Government  statistics  are,  and  vitiated  by  a  total  lack  of 
system  in  the  determination  of  the  actual  tonnage  treated  at  the 
mills,  yet  they,  too,  tender  an  emphatic  denial.* 

The  alleged  facts  are  further  explained  by  a  general  hypothesis 
that  the  gold  in  the  oxidised  ore  has  been  leached  out  so  that  it  is 
beneath  its  normal  richness,  which  will  be  found  nnimpaired 
below  the  water  level.  This  is  stated  to  be  evidenced  by  the 
removal  of  the  iron  pyrites,  the  casts  of  the  crystals  of  which  now 
appear  as  cavities  in  the  quartz.  In  some  of  these  gold  is  found, 
but  in  others  it  is  absent,  proving,  so  it  is  said,  that  the  gold  has 
been  removed  from  the  cavities  which  are  now  empty.  The  occur- 
rence of  films  of  fine  gold,  called  "  paint  gold,"  on  the  faces  of 
fractures  is  instanced  as  an  illustration  of  secondary  reactions. 
Finally,  the  alkaline  composition  of  the  waters  in  the  mines  is 
quoted  in  proof  of  their  solvent  power. 

Although  the  chemistry  of  the  oxidised  zone  is  far  from  being 
thoroughly  understood,  yet  in  its  incompleteness  it  is  sufficient  to 
disprove  these  arguments.  When  iron  pyrites  is  decomposed  the 
sulphide  becomes  a  sulphate,  and  this  in  turn,  by  further  oxida- 
tion in  the  presence  of  water,  is  resolved  into  sulphuric  acid  and 
the  hydrated  oxide  of  iron.  The  native  sulphur  frequently  seen 
in  the  cavities  left  by  the  removal  of  the  cubes  of  pyrites  is  not  a 
direct  product  of  decomposition,  but  is  traceable  to  later  secondary 
reactions  in  which  the  organic  matter  of  the  surface  has  served  as 
a  reducing  agent.  The  gold  intimately  mixed  with  the  pyrites, 
and  probably  originally  deposited  with  it,  remains,  because  the 
noble  metal  is  insoluble  to  the  waters  which  dissolved  the  iron. 

The  occurrence  of  gold  in  pyrites  is  now  less  of  a  mystery 
than  it  used  to  be.  Microscopic  examination  has  disclosed  the 
existence  of  the  gold  in  the  planes  of  the  pyrites,  and  the  leaching 
of  the  gold  by  cyanide  solutions  without  any  apparent  deformation 
of  the  pyrites  is  no  less  suggestive.  It  is  indeed  true  that  in  some 
of  the  casts,  left  by  the  removal  of  the  sulphides  gold  does  not 
occur,  but  this  is  frequently  due  to  the  fact  that  it  is  very  diffi- 
cult to  break  a  piece  of  cellular  quartz  without  shaking  the  gold 
out  of  the  cavities  in  which  it  lies  loosely.  Hence  their  emptiness 

*  Of  course  the  grand  totals  are  misleading,  since  they  include  the  produc- 
tion of  new  mines,  and  do  not  indicate  the  shutting  down  of  unprofitable  ones. 
The  yields  of  individual  mines  must  be  consulted. 


11 

may  mean  nothing.  At  other  times  this  may  indeed  be  due  to  the 
real  absence  of  the  gold,  and  against  this  observation  we  then 
balance  another,  namely,  that  the  pyrites  as  we  find  it  unaltered 
below  the  water  level  also  varies  in  its  gold  contents,  so  that  in 
the  same  vein  it  is  sometimes  barren  and  sometimes  rich,  account- 
ing in  this  way  for  the  uncertain  presence  of  free  gold  in  the 
oxidised  zone.  The  "paint  gold,"  frequently  noticed  in  the 
gossan,  appears  to  be  the  result  of  secondary  and  comparatively 
recent  reactions.  It  is,  however,  only  a  proof  of  precipitation, 
and  therefore  presupposes  a  previous  leaching,  but  not  necessarily 
in  the  vadose  region.  It  evidences  local  enrichment  rather  than 
impoverishment. 

Of  the  solvent  power  of  surface  waters  upon  the  gold  there  is 
only  supposition,  and  this  supposition  must  first  overcome  the 
fact  of  the  occurrence  of  such  organic  matter  in  the  ground 
approaching  the  surface  as  would  reduce  any  known  salts  of  gold 
should  they  be  in  solution.  In  the  Sugarloaf  Mine,  near  Kunanal- 
ling,  I  saw  the  roots  of  trees  at  74  ft.,  and  in  the  Great  Boulder 
Main  Reef  Mine,  at  Kalgoorlie,  I  saw  some  which  had  penetrated 
the  rock  to  85  ft.  below  the  surface.  In  the  former  case  the 
oxidation  of  the  enclosing  rock  ceases  at  130  ft.  and  in  the  latter 
at  175  ft.  The  region  is  an  unusually  dry  one,  which  has  under- 
gone erosion  with  extreme  slowness  ;  and  this  is  doubtless  the 
reason  why  roots  in  search  of  moisture  should  penetrate  so  deeply. 

The  waters  of  the  mines  are  all  brackish ;  they  are  many  times 
more  salt  than  the  sea.  Analyses  made  at  the  Great  Boulder 
Proprietary  Mine  show  an  average  in  solids  of  8'9  per  cent.,  and 
of  this  6*2  was  chloride  of  sodium,  0'45  chloride  of  magnesia,  and 
0'73  sulphate  of  lime.  The  water  from  the  Lane  shaft  gave  the 
maximum  of  11 '9  per  cent,  solids,  containing  S'S  N"aCl,  0'51  MgCl2, 
and  1-1  CaS04.* 

Certain  results  obtained  in  the  treatment  of  the  zinc  precipitate 
in  the  cyanide  works  of  the  Associated  Mines  have  led  the  mill 
manager,  Mr.  Grayson,  to  deduce  the  solubility  of  gold  in  sulph- 
uric acid  when  tellurium  oxide  is  also  present,  and  thus  to  offer  a 
chemical  theory  for  the  alleged  leaching  of  gold  in  the  surface 
ores.  This  explanation,  as  it  stands,  is  questionable,  because  the 
solubility  of  gold  under  the  stated  conditions  is  not  known. 
When,  however,  free  chlorine  is  also  present  such  solubility  would 
occur. f  The  telluric  oxide,  in  the  presence  of  salt  and  sulphuric 

*  For  these  figures  I  am  indebted  to  the  courtesy  of  Mr.  Kichard  Hamilton, 
the  mine  manager. 

f  As  pointed  out  by  Mr.  Richard  Pearce,  in  a  recent  letter  to  the  writer. 


12 

acid,  would  take  the  part  given  in  the  laboratory  to  the  black 
oxide  of  manganese.  The  occurrence,  therefore,  of  waters  rich  in 
chlorides,  of  sulphuric  acid  derived  from  decomposing  pyrites  and 
of  tellurium  oxide  obtained  from  the  oxidation  of  tellurides,  are 
all  recognisable  amid  the  conditions  at  Kalgoorlie,  and  thus  afford 
a  theory  which,  while  it  has  no  very  strong  evidence  to  commend 
it,  is  at  least  tenable  from  a  chemical  standpoint. 

In  many  cases  the  supposed  enrichment  in  depth  can  be  easily 
explained.  For  example,  a  shaft  passes,  in  course  of  sinking, 
from  poor  into  rich  ore.  The  lode,  it  would  appear,  has  become 
better  in  depth.  The  fact  is,  that  the  shaft  was  started  off  the 
oreshoot,  which  has  a  pitch  such  as  to  bring  it  across  the  line  of 
the  shaft  at  a  certain  level.  The  accompanying  diagram  will 
illustrate  this  point. 


MAIN    SHAFT 


It  would  be  just  as  reasonable  to  argue  that  the  ore  occurred 
in  vertical  bands  because  the  levels  pass  in  and  out  of  the  shoots. 
In  another  suggestive  instance  a  vertical  shaft  was  sunk  in  a  very 
wide  lode  which  is  not  quite  perpendicular.  The  shaft  was 
started  on  the  hanging  wall  side,  where  the  ore  is  now  known  to 
be  always  poor,  and  in  depth  it  approached  the  footwall,  where  the 
lode  is  richest.  It  was  assumed,  for  a  time,  that  an  enrichment 
in  depth  characterised  the  lode.  The  sketch  (p.  13)  will  explain 
this  occurrence. 

The  idea  of  general  enrichment  in  depth  at  Kalgoorlie  arises 
from  an  ignorance  of  the  history  of  the  early  development  of  the 
region.  The  discovery  of  the  big  ore-bodies  was  not  made  in  the 
infancy  of  the  district,  but  came  in  the  wake  of  that  preliminary 
digging  which  usually  precedes  systematic  exploration.  Patrick 
Hannan  pegged  out  the  first  claim  on  April  12th,  1892.  At  that 
time  nothing  was  known  save  the  existence  of  a  few  superficial 
deposits  on  the  flat  overlooked  by  Cassidy  Hill  and  Mount 
Charlotte.  These  deposits  were  of  the  kind  termed  "  dry  blowers' 
patches."  They  may  be  described  as  the  alluvium  of  a  waterless 


13 

country.  Their  substance  varies.  They  may  consist  merely  of 
a  few  inches  of  sand  and  clay  lying  on  the  decomposed  rock 
surface,  but  elsewhere  they  may  have  a  thickness  of  many  feet, 


SHAFT 


LODE 


and  include  a  lower  portion  which  is  so  compact  as  to  be  called 
"cement."  In  the  absence  of  the  transporting  power  of  running 
water,  the  wind  has  been  an  active  agent  in  sifting  the  debris 
caused  by  that  disintegration  of  the  surface  which  is  mainly  trace- 
able to  the  variation  between  the  heat  of  day  and  the  cold  of  night. 
The  finer  rock  particles  are  thus  separated  from  the  larger  frag- 
ments of  hard  quartz.  And  although  the  wind  is  but  a  feeble 
agent  as  compared  with  the  mountain  stream,  yet,  owing  to  the  pre- 
valence of  the  constant  and  violent  draughts  of  a  high  plateau, 
such  as  the  interior  of  West  Australia,  the  sum  of  its  activities 
during  long  periods  of  time  is  capable  of  producing  noteworthy 
results.  The  miner  imitates  the  ways  of  nature,  and  in  default  of 
sluicing  he  winnows  the  dirt  by  a  process  known  as  "  dry  blow- 
ing." The  "  dry  blower  "  of  West  Australia  is  brother  to  the 
"gulch  miner"  of  California  and  the  "alluvial  digger"  of  Vic- 
toria. 

From  the  deposits  which  are  thus  accumulated  gold  has  been 
extensively  won,  and  occasional  patches  of  extreme  richness  have 
been  encountered.  The  heaviest  gold  is  found  resting  close  to  the 
underlying  rock  surface,  and  therefore,  as  in  ordinary  alluvial 
mining,  the  working  of  these  deposits  often  leads  to  the  discovery 
of  the  veins  from  which  the  gold  was  shed.  Thus  many  "  dry 
blowers'  patches "  have  been  found  adjacent  to  very  valuable 
lodes,  and  in  the  case  of  the  alluvium  of  the  Kalgoorlie  flats 
there  were  found  small  veins  which  led  to  the  first  raining.  This 
early  mining  was  confined  to  that  portion  of  the  district  which  is 


14 

close  to  the  present  town  of  Kalgoorlie,  and  which  is  distinct  from 
the  scene  of  the  great  mining  developments  of  the  past  two  years, 
2  miles  further  to  the  southward.  The  veins  found  in  this 
northern  part  of  the  goldfield  were,  as  has  been  stated,  small ; 
they  were  also  uncertain  in  behaviour,  and  generally  poor.  They 
served  nevertheless  as  an  excuse  for  the  taking  up  of  numerous 
leases  and  the  subsequent  flotation  of  mining  enterprises  of  a 
thoroughly  worthless  kind.  Not  one  of  these  veins  has  as  yet 
become  the  basis  of  a  successful  enterprise,  although  they  have 
been  followed  by  very  extensive  workings.  In  the  meanwhile  the 
prospectors  wandered  further  south,  and  found  several  rich  patches 
of  surface  dirt  and  cement,  which  led  directly  to  the  discovery  of 
one  or  two  strong  quartz  croppings,  on  the  evidence  of  which  the 
Great  Boulder  and  other  claims  now  famous  were  pegged  out. 
These  quartz  veins  were  larger  than  those  previously  worked  in 
the  northern  part  of  the  field,  but  they  were  similarly  poor  and 
uncertain,  although  this  fact  did  not  prevent  the  notation  of  the 
Great  Boulder  Proprietary  Company.  The  story  of  this  splendid 
mine  is  typical  of  that  of  several  of  its  neighbours.  The  first 
explorations  were  confined  to  a  vein  which  outcropped  in  the 
eastern  part  of  the  lease,  and  the  shaft  sunk  upon  it  is  the  one 
known  as  No.  3,  or  Gamble  North's.  The  vein  was  soon  proved  to 
be  of  no  importance,  becoming  thin  and  poor  at  a  depth  of  75  ft. 
A  trench  was  then  started  to  cut  a  big  ironstone  outcrop  which 
forms  a  hillock  behind  the  present  office.  This  ironstone  reef  was 
found  to  contain  only  12  dwt.  of  gold  per  ton,  an  amount  too 
small  for  profitable  operations  at  that  time.  When,  however, 
the  trench  referred  to  was  extended  farther  west  it  penetrated 
another  vein  which  had  no  outcrop.  This  proved  to  be  the  eastern 
portion  of  the  magnificent  lode  which  subsequently  gave  such 
great  value  to  the  mine.  It  was  rich  from  the  start.  A  wide  open- 
cut  now  bears  confirmatory  evidence,  and  the  least  observant  can- 
not help  noticing  that  the  stopes  have  been  extended  from  the 
underground  workings  up  to  the  daylight.  The  section  afforded 
by  the  opencut  exhibits  the  fact  that  2£  ft.  of  cement  form  a  cap 
over  a  lode  nearly  20  ft.  wide.  The  Great  Boulder  Perseverance 
had  a  similar  beginning.  The  first  work  was  done  on  what  is  known 
now  as  the  old  No.  1  Shaft,  carrying  a  comparatively  poor  vein 
which  was  abandoned  when  the  rich  lode  in  the  neighbouring  Lake 
View  Consols  Mine  was  traced  into  the  Perseverance  ground.  This 
lode,  which  gave  the  value  to  this  company's  property,  also  failed 
to  outcrop.  A  big  opencut  now  explains  the  reason  to  be  similar 
to  that  noted  in  the  case  of  the  Great  Boulder.  The  surface 


15 

workings  on  the  Ivanhoe,  Kalgurli,  and  other  adjacent  mines 
exhibit  similar  conditions,  big  lodes  capped  by  cement  and  long 
lines  of  stopes  breaking  through  into  daylight. 

In  the  meantime  the  extensive  development  of  the  goldfield  has 
afforded  an  explanation  for  the  chequered  nature  of  the  early 
explorations.  It  has  been  found  that  the  quartzose  lodes  are 
uniformly  poor,  and  that  the  rich  ones  have  a  chloritic  and  mag- 
nesian  matrix  which  renders  them  susceptible  to  easy  degradation 
and  erosion.  Thus  it  is  easy  to  understand  the  current  misunder- 
standing. The  first  veins  worked  were  naturally  those  which  had 
outcrops.  They  outcropped  because  they  carried  much  quartz  and 
were  harder  than  the  encasing  country.  They  also  happened  to  be 
poor;  therefore  the  first  attempts  at  mining  were  unprofitable. 
On  the  other  hand  the  rich  lodes  had  a  composition  into  which  the 
carbonates  of  lime  and  magnesia  entered  largely,  rendering  them 
softer  than  the  rock  enclosing  them,  and  therefore  they  suffered 
erosion  at  least  as  rapidly  as  the  surrounding  country.  The 
detrital  deposits  of  the  surface  capped  the  tops  of  the  rich  ore- 
bodies,  and  it  was  not  until  an  accidental  exploration  had  pierced 
the  cap  of  this  "  cement "  that  the  first  of  the  soft  and  rich  lodes 
was  uncovered.  The  discovery  of  the  others  followed  in  due  course. 

The  idea  of  an  enrichment  in  depth  was  based  on  the  fact  that 
the  mines  which  were  at  first  unprofitable  became  subsequently 
marvellous  ore  producers.  Careless  observation  and  that  wishing 
which  is  father  to  much  loose  thinking  served  to  bolster  up  an 
erroneous  idea,  and  to  spread  the  statement  that  the  ore  became 
richer  at  the  water  level.  It  is  a  matter  which  does  not  affect  the 
reputation  of  the  really  good  mines  so  much  as  that  of  the  forlorn 
hopes,  the  poverty  of  which  is  excused  by  a  lack  of  depth,  thus 
leading  directly  to  the  spending  of  much  money  on  the  foundation 
of  a  fallacy. 

From  careful  investigation  and  the  sifting  of  much  evidence  I 
am  forced  to  the  conclusion  that  Kalgoorlie  is  no  exception  to  a 
common  experience,  and  that  where  rare  enrichments  occurred  in 
the  sinking  of  a  shaft,  the  fact  can  be  traced  to  the  structural  rela- 
tions of  the  ore  deposits.  I  regret  the  conclusion.  It  would  have 
encouraged  those  in  other  regions  had  there  at  last  been  found  a 
district  where  nature  had  placed  the  best  ore  where  man  could 
with  most  difficulty  reach  it,  and,  apart  from  its  economic  aspects, 
the  occurrence  would  have  been  one  of  great  scientific  interest. 

Thus  the  tellurides,  like  rhodochrosite,  tourmaline,  zinc  blende, 
pyrites  and  a  host  of  other  supposed  indicative  minerals,  must  be 
discarded  as  helps  no  better  than  the  will-o'-the-wisp  which  leads 


16 

the  wanderer  into  a  morass  worse  than  the  darkness  itself.    Better 
no  guide  at  all  than  a  false  one. 

Shareholders  and  investors  may  be  tempted  to  inquire  whether 
I  would  go  so  far  as  to  deny  the  possibility  of  veterans  in  the 
profession  having  such  ability  and  experience  as  would  permit 
them  to  come  to  safe  conclusions  as  to  the  prospective  value  of  a 
mine  from  a  mere  examination  into  the  character  of  the  ore.  To 
this  I  would  answer  that  I  believe  the  most  experienced,  the  very 
Ulysses  among  mining  engineers,  would  be  the  first  to  emphatic- 
ally disclaim  such  short  cuts  to  the  valuation  of  mines.  A  moil  and 
a  4-lb.  hammer  are  of  more  use  than  a  book  full  of  sounding  theories ; 
a  careful  sampling  of  the  workings  is  of  more  immediate  utility 
than  a  treatise  on  mineralogy.  Successful  mining  must  be  based 
on  facts ;  all  the  rhetoric  and  fond  imagining  in  the  world  cannot 
alter  them.  It  is  the  province  of  the  mining  engineer  to  deter- 
mine the  facts,  to  get  alongside  them,  as  Huxley  would  say,  and 
when  a  theory  comes  floating  by  leave  it,  as  Joseph  left  his  coat 
in  the  hands  of  the  harlot,  and  flee.  Experience  has  proved  thab 
indicative  minerals  are  delusive  ;  so  let  them  go.  But  the  mineral 
contents  of  an  ore,  though  they  have  no  bearing  on  the  mining, 
decide  its  metallurgical  treatment,  and  therefore  need  careful 
examination.  The  importance  of  the  character  of  the  ore  from 
this  point  of  view  is  too  often  overlooked  by  those  enthusiastic 
mineralogists  who  permit  themselves  to  make  the  most  sweeping 
deductions  on  matters  of  much  greater  uncertainty. 

Careful  sampling  is  worth  a  bushel  of  suppositions,  and  the 
painstaking  determination  of  the  working  costs  is  better  than  any 
amount  of  geological  generalisation.  Mining  is  not  a  scientific 
pursuit,  although  at  times  it  may  to  the  observant  have  seemed  to 
be  either  that  or  one  big  insanity.  But  mining  is  an  industry. 
The  good  sense  which  financial  men  have  of  late  years  contributed 
to  its  operations  has  done  much  to  bring  it  from  a  windy  misti- 
ness to  the  solid  footing  of  sound  business  The  main  purpose 
is  not  to  develop  the  waste  places  of  the  earth,  nor  to  spoil  the 
scenery  of  the  mountainous  ones,  but  simply  to  win  a  profit  by 
extracting  ores  out  of  the  ground.  It  is  a  plain  matter  of  profit 
and  loss.  On  the  one  side  is  the  value  of  the  gold  in  the  ore,  and 
on  the  other  is  the  cost  of  the  processes  needed  to  obtain  it.  To 
arrive  at  the  former  there  is  only  one  way,  namely,  to  sample  the 
workings  systematically.  The  result  will  be  reliable  in  propor- 
tion to  the  care  taken.  Any  shirking  of  difficult  places  in  the 
mine,  any  avoidance  of  hard  portions  of  the  vein,  any  assistance 
from  untrustworthy  hands,  will  vitiate  the  resulc.  Against  this 


17 

must  be  placed  the  costs  of  operation.  Here  it  is  that  experience 
is  needed.  The  sampling  is  largely  mechanical,  like  ordinary- 
assaying",  and  requires  patience  and  care  more  than  anything  else. 
In  the  estimate  of  the  costs  there  must  be  included  many  items  of 
expenditure,  such  as  the  breaking  of  the  ore,  the  development 
work,  the  equipment,  the  milling,  the  management ;  and  to  arrive 
at  these  the  previous  actual  charge  of  mines  is  the  only  proper 
preparation.  Then  comes  the  question  of  the  quantity  of  ore  avail- 
able or  likely  to  become  available  by  further  exploration.  This  is 
the  pans  asinorum  of  mining.  That  which  some  describe  as  ore  in 
sight  is  often  really  ore  out  of  sight.  The  over  sanguine  estima- 
tion of  ore  reserves  has  rained  more  enterprises  than  all  the  bad 
management  and  over- capitalisation  of  which  complaints  are  daily 
made.  It  is  ever  a  difficult  matter  and  requires  a  cool  judgment, 
wide  experience,  and  a  careful  investigation  into  the  circum- 
stances and  structure  of  each  particular  mine. 

When  the  value  and  tonnage  of  the  ore  available  have  been 
arrived  at,  and  when  working  costs  have  been  determined,  then 
the  engineer  has  the  greater  part  of  the  evidence  needed  to  submit 
to  the  client  whom  he  is  advising.  The  other  data  which  will 
influence  an  opinion  are  more  variable  in  their  character.  The 
geological  conditions  may  affect  the  distribution  of  the  ore  bodies 
and,  consequently,  the  cost  of  mining,  and  the  mineralogical  com- 
position of  the  ore  may  determine  the  expense  of  milling.  As 
such  they  mast  not  be  overlooked,  but  the  padding  of  a  report 
with  a  large  amount  of  geological  disquisition,  where  it  is  not 
necessary  to  a  comprehension  of  the  facts  of  the  case,  is  very 
nearly  an  impertinence,  seeing  that  it  is  not  expected  that  it  will 
be  understood  by  the  person  or  persons  for  whose  guidance  the 
report  is  written. 

In  concluding  this  contribution  I  would  express  the  hope  that 
this  paper  may  lead  to  a  useful  discussion.  If  there  are  any  tech- 
nical men  who  seriously  entertain  the  idea  of  an  enrichment  in 
depth  due  to  the  leaching  of  gold  in  the  oxidised  ores,  then  it  would 
be  of  much  service  to  the  industry  if  they  would  frame  a  defence 
and  an  explanation  of  views  which  daily  experience  must  other- 
wise condemn  as  nonsense.  Nor  in  denouncing  one  generalisation 
would  I  make  the  equally  grave  mistake  of  advocating  its  opposite, 
namely,  that  all  mines  must  necessarily  become  poorer  in  depth. 
There  may  be  causes,  founded  on  geological  structure,  why  a 
change  in  the  value  of  the  ore  in  a  vein  may  take  place  in  any 
direction,  upward  or  downward,  in  dip  or  in  strike,  and  it  is  an 
undoubted  fact  that  there  have  been  instances  where  the  deepening 


18 

of  the  workings  lias  led  to  the  discovery  of  new  ore  bodies.  Bendigo 
is  a  telling  illustration.*  The  gold-bearing  quartz  occurs  along  the 
anticlinal  axes  of  sedimentary  rocks.  In  sinking,  a  succession  of 
saddle  formations  is  penetrated.  ~No  single  one  of  these  has  any 
not  able -vertical  extent,  yet  the  series  as  a  whole  is  wonderfully 
persistent.  This  explains  why  the  last  resort  of  a  perplexed  mine 
manager  is  to  advise  the  sinking  of  the  main  shaft.  At  Bendigo 
the  advice  is  well  founded,  but  when  the  managers  from  this  dis- 
trict go  to  West  Australia  and  recommend  deeper  exploration 
every  time  they  encounter  poor  ore,  they  do  so  without  regard  to 
the  total  unlikeness  of  the  conditions.  Again,  it  cannot  be  denied 
that  in  certain  regions  alternations  of  comparative  richness  and 
poverty  appear  to  coincide  with  the  penetration  of  the  workings 
through  successive  zones  of  rock.  The  Gympie  district  is  a  case 
in  point.  There  the  veins  cut  through  a  series  of  shales,  lime- 
stones, conglomerates,  and  sandstones,  amid  which  there  are 
several  beds  of  black  slate.  The  gold  occurs  in  paying  quantity 
only  when  the  veins  are  traversing  the  slates.  Every  district 
deserves  a  study  unbiassed  by  the  record  of  its  neighbours  ;  each 
mine  must  be  taken  on  its  merits  and  inspected  without  prejudice. 
It  is,  however,  one  thing  to  examine  a  mine  with  the  assumption 
that  gold  veins  in  general  become  enriched  in  depth,  and  it  is 
quite  another  thing  to  recognise  that  while  it  may  occur  in  a  par- 
ticular case,  it  is  an  expectation  which  experience  does  not  justify. 
When,  however,  such  enrichment  or  impoverishment  does  occur, 
experience  suggests  to  us  that  its  cause  is  to  be  sought  for  rather 
in  the  geological  structure  of  the  encasing  rocks  than  in  the 
merely  coincident  presence  of  certain  minerals  found  associated 
with  the  gold. 

*  See  "  The  Bendigo  Goldfield,"  by  the  writer,  in  vol.  xx,  Trans.  Amer.  Inst. 
of  Mining  Engineers. 


HARRISON  AND  SONS,  Printers  in  Ordinary  to  Her  Majesty,  St.  Martin's  Lane. 


Abstract  of  Proceedings.— Vol.  VIII. 


"The  Cripple  Creek  Goldfield,' 


A  PAPER  READ   BEFORE   THE 

INSTITUTION  OF  MINING  AND  METALLURGY, 

ON  WEDNESDAY,  IOTH  NOVEMBER,  1899, 

BY 

T.  A.  RICHARD,  M.Inst.M.lVL,  State  Geologist  of  Colorado. 


Bonbon : 

INSTITUTION  OF  MINING"  AND  METALLURGY, 
BROAD  STREET  HOUSE,  B.C.  ' 


"  The  Cripple  Creek  Goldfield." 
By  T.  A.  RICKARD.,  M.Inst.M.M.,  State  Geologist  of  Colorado. 

INTRODUCTORY. 

THE  romantic  history  of  mining  records  many  names  which  had  an 
odd  sound  until  fame  familiarised  them.  Ballarat,  the  Coeur 
d'Alene,  Bendigo,  the  Yuba,  Leadville,  Broken  Hill,  Klondyke,  and 
Kalgoorlie,  for  example,  have  been  words  to  conjure  with,  although 
in  the  beginnings  of  the  particular  mining  districts  designated  by 
them  they  were  spelt  with  difficulty  and  pronounced  with  un- 
certainty. In  1892,  when  Cripple  Creek  began  to  be  talked  about 
among  the  clubs  and  banks  of  Denver,  as  a  new  locality  where  im- 
portant discoveries  of  gold  had  been  made,  the  name  seemed  only 
provocative  of  derision.  It  is  said  to  have  originated  from  the  fact 
that  at  a  certain  point  on  the  course  of  the  little  stream  there  was  a 
morass  in  which  straying  cattle  wandered  and,  in  their  efforts  to 
extricate  themselves,  were  occasionally  lamed.  So  says  one  of  the 
survivors  of  the  band  of  men  who  once  tended  the  herds  that 
grazed  on  the  hills  now  pierced  with  many  shafts.  However,  the 
name  needs  no  apology  to-day,  the  magic  baptism  of  golden  dis- 
covery has  made  it  sound  as  alliterative  and  impressive  as  the  most 
exacting  historian  could  demand. 

The  locality  of  the  great  goldfield  is  full  of  romantic  suggestion, 
because  its  very  situation,  overshadowed  by  the  granite  battlements 
of  Pike's  Peak,  recalls  the  fact  that  it  has  fulfilled  the  expectations 
of  an  older  generation.  The  wave  of  immigration  which,  after  the 
financial  panic  of  1857,  swept  westward  until  it  broke  against  the 
ramparts  of  the  Rocky  Mountains,  was  the  vanguard  of  a  new 
civilisation  destined  to  dispossess  the  Indian  and  the  buffalo.  In 
their  progress  across  the  prairies,  the  pioneers  of  that  advance  ever 
sought  with  shaded  eyes  for  the  first  glimpse  of  the  beacon  moun- 
tain whose  white  crest  on  the  far  horizon  gave  promise  of  the  land 
of  gold.  That  beckoning  guide  was  the  granite  peak  which  Lieut 

6 


Zebulon  Pike  had  reconnoitred  in  the  first  years  of  the  century. 
"  Pike's  Peak  or  bust,"  the  motto  of  the  adventurers  of   1857  and 

1858,  sounds  but  mock  heroic  in  our  ears,  but  it  expressed  something 
of  the  mingled  humour  and  daring  of  the  men  who  first  pierced  the 
unknown  wilderness  which  was  then  the  borderland  of  the  territory 
of  Kansas. 

The  immigration  which  marked  the  beginning  of  Colorado's 
history,  was  thus  known  as  "  the  Pike's  Peak  excitement."  The 
rallying  call  of  the  pioneers  expressed  a  delusion.  No  gold 
discoveries  of  any  moment  were  made  at  that  time  in  the 
canyons  or  on  the  hills  surrounding  the  peak.  It  was  in  the 
mountainous  region  70  miles  northward,  now  known  as  Gilpin 
County,  that  the  first  beginning  was  made.  On  the  6th  of  May, 

1859,  John   Hamilton   Gregory   found   the    outcrop  of    the   lode 
which  still  bears  his  name  and  the  working  of  which  celebrated  the 
commencement  of  the  mining  industry  of  Colorado.     This  discovery 
led  to  the  development  of  Gilpin  county,  which  was  contempor- 
aneous with  the  opening  up  of  Clear  Creek  and  Boulder.     In  1860 
the  placers  of  California  gulch  and  Breckenridge  were  discovered ; 
in  1875,  Leadville;  in  1879,  Aspen;  in  1882,  Eed  Mountain;  in 
1889,  Creede;  and  so  on,  until  the  mining  districts  of  Colorado 
were  distributed  all  over  its  wonderful  complex  of  mountain  land. 

Amid  all  these  rapidly  succeeding  discoveries,  and  the  extra- 
ordinary activity  which  followed  each  of  them,  the  silence  of  the 
quiet  hills  surrounding  Pike's  Peak  remained  unbroken.  Suddenly, 
in  the  spring  of  1884,  rumours  were  circulated  of  a  great  discovery 
south  of  the  peak.  During  the  darkness  of  an  April  night  a  horde 
of  prospectors  stole  swiftly  away  in  obedience  to  vague  hints  which 
had  been  scattered  among  the  saloons  of  Leadville  and  surrounding 
camps.  Each  party  aimed  to  be  the  first  on  the  ground.  The 
dawn  of  the  next  day  found  an  excited  crowd  of  four  thousand  men 
gathered  at  the  base  of  Mt.  Pisgah.  The  incident  has  since  become 
known  in  local  history  as  the  Mt.  Pisgah  fiasco. 

Among  the  hills  which  like  a  flock  of  sheep  cluster  around  the 
southern  base  of  Pike's  Peak,  there  is  a  dark  cone  standing  in  soli- 
tude among  its  smaller  brethren.  This  is  Mt.  Pisgah.  In  1884 
the  miners  who  rushed  thither  could  find  no  gold  in  workable 
quantity  save  in  the  prospect  holes  made  by  the  original  locators. 
Salting  was  suspected,  the  man  who  had  instigated  the  rush  was 
conspicuous  by  absence,  an  accomplice  was  caught  with  a  bottle  of 
yellow  stuff  in  his  pocket.  It  was  not  whisky,  but  its  modern 
antidote,  the  chloride  of  gold.  Man  had  endeavoured  to  remedy 
nature's  seeming  niggardliness  and  the  rock  had  been  artificially 


enriched.  Angry  feelings  found  vent  in  threats  of  lynching,  but  in 
the  failure  to  lay  hands  upon  the  real  perpetrators  of  the  fraud, 
the  affair  broke  up  in  a  big  picnic  and  a  general  drunk.  A  little 
digging  had  been  done,  one  or  two  veins  were  uncovered,  but  the 
comparative  poverty  of  the  ore  only  added  bitterness  to  the  general 
disappointment.  The  crowd  disappeared  as  quickly  as  it  had  come. 
The  hillsides  resumed  the  quiet  aspect  of  the  cattle  range  for  which 
they  seemed  best  fitted.  The  incident  was  over. 

The  vicissitudes  of  mining  are  proverbial.  No  district  illus- 
trates it  more  forcibly  than  Cripple  Creek.  It  provokes  one  to 
cynicism  to  think  how  near  the  deluded  prospectors  of  1884  were 
to  the  eve  of  big  discoveries.  The  dark  front  of  Mt.  Pisgah  now 
overshadows  the  very  streets  of  the  town  of  Cripple  Creek,  with  its 
20,000  inhabitants,  and  on  the  ridges  opposite  the  lines  of  smoking 
chimneys  bespeak  a  long  succession  of  productive  mines. 

Not  until  1893  did  Cripple  Creek  come  to  the  front;  two  years 
before,  the  name  had  begun  to  be  mentioned  in  mining  circles,  but 
the  Mt.  Pisgah  excitement  had  discredited  the  district  and  the 
contemporaneous  discoveries  of  large  silver  lodes  at  Creede,  at  the 
headwaters  of  the  Eio  Grande,  diverted  attention  for  a  time.  The 
closing  of  the  Indian  mints,  in  June,  1893,  prostrated  the  silver 
mining  industry,  which  at  that  period  was  far  more  important  to 
the  state  than  its  gold  production.*  As  soon,  however,  as  the  silver 
market  became  disorganized,  all  the  activity  of  a  most  energetic 
mining  community  was  concentrated  upon  its  gold  resources.  The 
experienced  men  of  Leadville  and  Aspen,  where  silver-lead  mining 
predominated,  turned  with  the  energy  of  despair  to  the  new  gold- 
field  which  previously  they  had  pooh-poohed.  A  new  impetus  was 
given  to  exploratory  work,  Cripple  Creek  underwent  rapid  develop- 
ment and  the  result  soon  became  apparent  in  the  opening  up  of 
several  rich  mines  and  in  a  production  of  gold  which  sprang  from 
$583,000  in  1892  to  $2,100,000  in  the  year  following. 

A  few  notes  regarding  the  events  which  led  up  to  the  present  era 
of  prosperity  and  productiveness  will  fittingly  close  this  introductory 
history.  For  several  years  before  1891  prospectors  had  wandered 
over  the  hills  from  Colorado  Springs  and  Florissant,  treading  in  the 
footsteps  of  the  men  of  1858.  Indeed,  there  is  a  story  current  in 
the  camp  to  this  day  that  on  the  top  of  Bull  Cliffs,!  above  the  Victor 

*  In  1892,  Colorado  produced  26,350,000  oz.  of  silver,  valued  at  $23,082,600, 
and  256,410  oz.  of  gold,  worth  $5,300,000.  In  1898  the  State  producer) 
1,138,584  oz.of  gold,  worth  823,534,531. 

t  The  names  of  several  hills  and  gulches  are  reminders  of  the  fact  that  the 
district  was  once  given  up  to  the  quiet  herds  of  cattle. 

6  2    ' 


Mine,  there  was  found  a  shallow  shaft,  which  had  been  dug  by  the 
pioneers  of  the  Pike's  Peak  excitement.  Among  the  earliest  of  the 
gold-seekers  was  Robert  Womack,  who  once  owned  a  small  ranch  in 
the  district.  He  sold  it  to  Bennett  and  Myers,  the  proprietors  at 
that  time  of  the  cattle  range,  which  covered  a  large  part  of  the  area 
now  forming  the  environs  of  the  town  of  Cripple  Creek.  For  many 
years,  between  1880  and  1890,  Bob  Womack  lived  in  the  district, 
doing  occasional  work  for  Bennett  and  Myers,  and  spending  his 
spare  time  in  prospecting.  He  had  previously  had  some  experience 
in  Gilpin  County,  and  knew  gold  ore  when  he  saw  it.  In  the  course 
of  desultory  digging,  he  found  several  veins,  and  when  he  would 
turn  up  at  intervals,  at  Colorado  Springs,  he  exhibited  pieces  of 
float  (surface  ore)  as  evidence  of  his  discoveries ;  but  having  a  repu- 
tation for  honesty  rather  than  shrewdness,  his  statements  made  little 
impression.  For  many  years  he  worked  on  a  hole  in  Poverty  Gulch 
without  staking  a  claim  in  proper  form.  There  seemed  no  need  to 
do  so ;  no  one  came  to  disturb  him ;  the  whole  hill  country  was  at 
that  time  fenced  in  so  as  to  serve  as  a  summer  range  for  cattle.  The 
cowboys  and  herdsmen  looked  good-naturedly  at  Bob's  digging,  but 
did  not  consider  it  of  any  moment.  In  December,  1890,  E.  M.  de 
la  Vergne  and  F.  F.  Frisbee  came  up  from  Colorado  Springs  to 
prospect.  George  Carr,  who  was  in  charge  of  the  ranch  belonging 
to  Bennett  and  Myers,  showed  them  around  the  district.  The  hills 
were  under  snow,  and  only  a  few  bare  spots  permitted  of  any  pro- 
specting. On  Guyot  Hill,  in  Eclipse  and  in  Poverty  Gulches,  they 
found  evidences  of  gold  veins,  and  samples  were  taken  away.  These 
averaged  about  2  oz.  of  gold  per  ton.  Encouraged  by  their  first 
visit,  De  La  Vergne  and  Frisbee  returned  early  in  February,  1891. 
They  found  Bob  Womack  at  work  in  Poverty  Gulch.  He  had  sunk 
a  shaft  to  a  depth  of  48  ft.,  and  encountered  good  ore.  The  claim 
he  had  pegged  out  was  called  the  "  Chance,"  and  a  number  of 
stakes  indicated  that  he  had  relocated  it  six  years  in  succession 
without  recording  the  fact  or  complying  with  the  conditions  of  the 
mining  law  in  regard  to  the  amount  of  assessment  work  required 
annually.  When  he  found  the  newcomers  were  making  inquiries, 
he  relocated  the  claim  as  the  "  El  Paso,"  and  De  La  Vergne,  finding 
another  lode,  heavy  in  iron  pyrites,  to  the  west  of  Womack's  vein, 
located  a  claim,  which  he  called  the  "  El  Dorado."  It  was  recorded 
a  few  days  later,  and  in  the  certificate  the  district  was  called  for  the 
first  time  by  the  name  which  it  still  bears,  Cripple  Creek.  Although 
these  locations  had  been  made,  little  actual  mining  was  done  upon 
them  for  some  time  afterwards.  Womack  absented  himself.  Frisbee 
saw  that  there  was  a  good  deal  of  surface  ore  which  could  easily 


be  removed,  so  while  Womack  was  away,  he  sent  1,100  Ib.  by  wagon 
to  the  Pueblo  Smelting  and  Kefining  Company,  who  gave  returns  at 
the  rate  of  $200  per  ton.  This  was  in  August,  1891.  Frisbee 
induced  Womack  to  give  him  a  bond  and  option  on  the  El  Paso  for 
•85,000.  Shortly  afterwards  it  was  transferred  to  Messrs.  Lennox 
and  Giddings,  who  still  own  it,  as  a  part  of  a  very  successful  mine, 
the  Gold  King. 

In  May,  Frisbee  and  De  La  Vergne  happened  to  be  at  Colorado 
Springs  and  met  "\V.  S.   Stratton,  to  whom  they  showed  certain 
assays  of  ores  brought  down  by  them  from  Cripple  Creek.    Stratton 
was  a  house-builder  and  carpenter  by  trade,  but  in  the  intervals  of 
his  regular  occupation  he  had  been  prospecting  for  fully  20  years 
previous  to  this  date ;    he  had  learnt  the  use  of  the  blow-pipe,  and 
was  familiar  with  the  outlines  of  mineralogy  and  geology,  in  fact 
an  energetic,  well-informed  man,  thoroughly  equipped  for  prospect- 
ing work  of  any  kind.      At  that  time  he  had  been  searching  for 
cryolite,  a  mineral  from  which  the  metal  aluminium  is  obtained, 
and  had  a  camp  on  the  Little  Beaver,  on  the  Cripple  Creek  side  of 
Pike's  Peak.      After  the  meeting  with  De  La  Vergne  and  Frisbee, 
he  went  to  Cripple  Creek  and  camped  there.     Stratton  met  Bob 
AVomack  and  went  around  seeing  the  little  work  done  by  the  latter 
and  his  associates.      Among  those  who   were  prospecting  in  the 
vicinity  was  Dick  Houghton,  an  old  mountaineer,  prospector,  and 
specimen  hunter,  whose  labours  have  enriched  many  museums.    One 
day  Houghton  brought  down  a  piece  of  rock  from  the  Lone  Star 
claim  on  Gold  Hill,  and,  meeting  Stratton  in  Poverty  Gulch,  he 
told  him  he  had  found  some  galena  (the  sulphide  of  lead).    Stratton 
examined  it  with  his  magnifying  glass  and  expressed  doubts  as  to 
its  being  galena,  and  in  looking  at  the  ore  he  saw  little  cubes  of 
rusty  gold,  one  of  which  had  been  scratched  by  being  carried  in 
Houghton's  pocket  so  as  to  expose  a  bright  surface.     They  went 
down  to  Stratton's  tent,  and  he  pulled  out  his  blow-pipe  and  made 
a  test  which  proved  that  it  was  gold.      Neither  of  these  men  knew 
at   that  time  that   the   bright   silvery   mineral,   which   Houghton 
thought  to  be  galena,  was  sylvanite,  the  telluride  of  gold  and  silver. 
It  is  not  known   who   first  recognised   the   tellurides  of   Cripple 
Creek,  but  there  is  a  story  that  a  miner  made  a  camp  fireplace  with 
some  pieces  of  rock  which  carried  this  silvery  mineral,  and  that  the 
heat  of  his  cooking  operations  roasted  the  ore  so  as  to  bring  out  the 
fact  that  it  carried  gold.      Se  non  k  vero  e  ben  trovato.      Stratton 
went  up  and  located  the  claim  adjacent  to   Houghton's;    it  was 
named  the  Gold  King,  and  is  now  a  part  of  the  Gold  and  Globe 
property.      On  the  5th  of  June,  Stratton,  accompanied  by  Fred 


6 

Troutman,  went  to  the  ridge  above  Battle  Mountain,  and  seeing 
the  willows  at  the  head  of  Wilson  Creek  (where  now  the  town  of 
Goldfield  is  situated),  they  inferred  the  presence  of  water.  They 
descended  the  hill  and  got .  a  drink ;  then  climbing  the  hill  behind 
the  spring,  they  found  loose  pieces  of  rock,  one  of  which  was 
broken  open  and  found  to  be  smothered  in  gold.  The  owner  of 
the  Independence  says  that  this  was  the  only  time  he  got  really 
excited.  Camp  was  moved  from  Cripple  Creek  next  day  and 
pitched  close  to  the  spring.  A  search  was  begun  for  the  lode  which 
had  shed  so  goodly  a  float.  Trenches  were  dug  ;  but  Stratton  had 
an  idea  at  this  time  that  veins  with  a  north  and  south  direction 
were  the  ones  which  carried  rich  ores,  and  so  his  trenches  were  dug 
at  right  angles  to  this  course,  with  the  result  that  they  paralleled 
the  veins  actually  existing  there,  and  since  developed  into  the 
Legal  Tender,  Lillie,  and  Vindicator  Mines.  They  found  nothing. 
An  old  ranchman,  Billy  Fernay,  came  along  about  this  time  and 
brought  some  float  which  he  had  found  on  the  hill  below,  now 
called  Battle  Mountain.  Stratton  liked  the  look  of  it,  so  Fernay 
located  it  for  Stratton,  Troutman,  and  himself,  calling  it  the  Black 
Diamond.  It  is  now  one  of  the  claims  included  within  the  territory 
of  the  Portland  Mine.  Next  day  Stratton  went  down  to  see  the 
vein  and  tried  to  make  the  course  of  it  accord  with  the  line  of  the 
ridge.  This  led  him  down  the  hill  to  a  big  outcrop  of  granite.  It 
was  the  Independence  vein,  which  had  already  been  seen  by  many, 
including  nearly  all  of  those  whose  names  have  been  mentioned. 
The  path  from  one  ranch  to  another  went  close  by,  and  all  the 
cattle  men  who  had  any  idea  of  prospecting  had  looked  at  it. 
Every  one  had  condemned  it  as  worthless  granite.  Fernay  pointed 
it  out  to  Stratton,  but  he  also  did  as  the  others  had  done.  On 
examining  the  outcrop  he  remarked  the  absence  of  any  metallic 
mineral  and  of  vein  quartz  such  as  he  had  been  accustomed  to  in 
the  San  Juan  region,  and  therefore  concluded  that  it  was  an 
unlikely  looking  rock.  And  so  it  really  was,  for  it  was  granite 
without  the  ordinary  gold-bearing  minerals  visible  in  it,  differing 
indeed  from  the  granite  of  the  dome  of  Pike's  Peak  in  being  less 
fresh  in  appearance,  brown  instead  of  pink,  and  marked  by  dark 
spots  where  the  mica  had  been  decomposed.  Some  of  it  yet 
remains  in  place,  inviting  the  observation  of  those  who  may  wonder 
why  the  great  lode  was  so  long  disregarded.  Stratton  overlooked 
it,  but  not  irretrievably.  Two  days  later,  John  R.  McKinnie,  who 
was  one  of  the  first  prospectors  in  the  district,  came  to  their  camp, 
and  so  did  Charlie  Love,  a  ranchman  from  Beaver  Park,  who  had 
pointed  out  the  big  outcrop  to  many  of  the  prospectors.  The  latter 


asked  McKinnie  if  he  had  seen  it,  but  the  matter  was  allowed  to 
drop.  Stratton  remembered  the  incident  when,  on  the  morning  of 
the  Fourth  of  July,  he  was  at  Colorado  Springs,  whither  he  had  gone 
with  five  samples  for  assay.  The  assays  gave  only  three  or  four 
dollars  per  ton  at  the  best,  notwithstanding  that  he  had  obtained 
good  results  by  panning.  It  suddenly  occurred  to  him  that  the 
granite  outcrop  must  be  the  lode.  He  had  found  gold  in  the  loose 
fragments  of  porphyry  lying  upon  the  south  face  of  Battle  Mountain 
near  the  granite  outcrop,  but  he  had  been  unable  to  trace  its  source 
to  any  vein  in  the  porphyry  formation.  Acting  on  the  impulse,  he 
took  a  horse  immediately,  and  on  arrival  found  Troutman  ready 
to  leave  in  order  to  celebrate  the  Fourth  at  Colorado  Springs. 
Stratton  made  two  locations  :  the  Washington  and  the  Independ- 
ence. I  doubt  if  any  man  ever  celebrated  the  Fourth  of  July  to 
better  advantage.  Some  pieces  of  the  outcrop  of  granite  ore  were 
broken,  and  Troutman  took  them  to  be  assayed  at  the  Springs, 
while  Stratton  awaited  the  result.  Troutman  returned  on  horse- 
back next  day  with  the  assay  certificate,  proving  the  ore  to  be 
worth  |380  per  ton  !  The  rest  of  the  story  is  simple.  It  records 
the  steady  development  of  one  of  the  richest  mines  ever  uncovered 
by  the  miner's  pick. 

I  might  go  on  to  tell  the  story  of  the  Portland  and  that  of  other 
mines,  now  celebrated,  which  made  beginnings  no  less  romantic ; 
but  the  above  few  notes  will  give  an  idea  of  the  manner  in  which 
the  Cripple  Creek  goldfield  was  first  opened  up.  Let  me  emphasize 
the  fact  that  it  was  not  the  result  of  accident,  nor  the  work  of 
ignorant  men,  but  it  was  the  accomplishment  of  experienced  miners 
who  knew  what  they  were  doing,  and  had  the  energy  and  ability  to 
do  it.  It  is  now  a  part  of  the  true  and  romantic  story  of  beneficent 
endeavour  which  turned  the  barren  prairies  into  the  granary  of  a 
continent,  and  made  the  snowclad  mountains  an  empire  whose  tribute 
of  gold  and  silver  transcends  that  of  the  Caesars'. 

PHYSICAL  FEATURES  OF  THE  DISTRICT. 

The  known  gold-bearing  portion  of  the  district  covers  an  area 
four  miles  long  by  three  miles  wide,  occupying  a  group  of  hills 
which  rise  from  300  ft.  to  1,000  ft.  above  the  general  surface, 
and  have  an  average  altitude  of  10,500  to  11,000  ft.  above  the  sea. 
The  drainage  of  the  region  flows  into  the  Arkansas  river,  whose 
gateway  into  the  plains  is  at  Canon  City.  The  general  slope  is 
southward,  and  the  sunny  aspect  incident  to  this  configuration  of 
the  surface  has  caused  the  hill-sides  to  be  clad  with  sufficient  grass, 


8 

and  rendered  them,  at  one  time,  despite  the  high  altitude,  a  good 
pasturage  for  cattle. 

Few  mining  camps  have  so  picturesque  a  situation,  and  Cripple 
Creek  is  further  notable  because  the  picturesque  is  not  obtained  at 
any  sacrifice  of  accessibility.  The  beauty  of  the  panoramic  view  to 
be  obtained  from  most  of  the  mines  is  not  due  to  mere  ruggedness 
or  to  the  ordinary  grandeur  of  a  mountainous  country ;  it  is  trace- 
able to  a  position  upon  the  slopes  flanking  Pike's  Peak,  which  per- 
mits of  an  uninterrupted  view  of  snow-clad  ranges  a  hundred  miles 
away.  It  is  a  panorama  rather  than  a  picture.  In  front  are  hills 
like  giants  tumbled  in  troubled  sleep,  whose  feet  touch  the  plateau 
of  the  South  Park.  To  the  left  are  the  Arkansas  hills  that  confine 
the  river  of  the  same  name  to  its  tumultuous  gorge ;  further  south 
is  the  Wet  Mountain  valley,  and  beyond  that  the  long  magnificent 
serrated  range  of  the  Sangre  de  Cristo,  telling  of  the  shattered  dream 
of  Spanish  conquest,  of  which  no  trace  now  survives,  save  in  the 
occasional  name  of  a  peak  or  a  stream.  These  remind  a  practical 
age  of  the  priestly  warriors  and  the  warlike  priests  who  once  sought 
to  win  the  golden  treasures  of  a  land  whose  aboriginal  people  have 
almost  passed  away.  The  wind  blows  the  snow  of  the  Sangre  de 
Cristo  into  streaming  banners,  and  the  clouds  like  vanquished  legions 
sweep  across  the  far  horizon.  Turning  northward,  the  valley  of  the 
Arkansas  can  be  seen  dividing  the  mountains  which  overlook  Lead- 
ville.  Further  to  the  right  are  the  beautiful  Kenosha  hills,  at  the 
headwaters  of  the  Platte,  and  beyond  them  are  snow-clad  peaks 
rising  above  14,000  ft.  The  details  of  the  view  are  lost  in  the  vast- 
ness  of  it,  which  impresses  the  observer  no  less  because  he  is  sur- 
rounded by  a  noisy  murmur  of  trains,  steam  whistles,  wagons,  and 
machinery,  which  tell  of  the  activity  going  on  about  him.  Still, 
there  is  a  nobility  of  human  endeavour  and  successful  achievement 
no  less  impressive  than  the  beauty  of  snow-clad  peak  and  silver 
summits. 

The  physical  condition  of  the  surface  had  much  to  do  with  the 
chequered  history  of  the  district.  Owing  to  the  southern  exposure 
and  the  comparative  absence  of  a  protecting  growth  of  trees,  the 
rocks,  which  mostly  possess  a  fissile  structure,  have  been  shattered 
by  frost  so  as  to  overspread  the  solid  formation  with  a  thickness  of 
debris  to  which  the  tufted  grass  has  given  a  further  covering. 
Water,  owing  to  its  expansion  between  4°  C.  and  the  freezing  point, 
is  a  ceaselessly  destructive  agent.  When  it  penetrates  the  cracks 
and  crannies  of  the  rocks  it  serves  as  a  wedge  shattering  their  stony 
substance  with  a  resistless  power.  The  heat  of  day  and  the 
cold  of  night,  the  warmth  of  summer  and  the  snows  of  winter,  alike 


9 

aid  this  disintegrating  process.  A  high  altitude  and  a  south  slope 
afford  the  conditions  most  favourable  to  such  action.  Thus  it  came 
about  that  the  district  of  Cripple  Creek  is  largely  covered  with  the 
shattered  rock  which  the  miners  call  "  wash,"  incorrectly,  however, 
because  it  is  not  composed  of  rounded  waterworn  material,  but  of 
angular  fragments  which,  if  not  in  place,  are  not  far  from  their 
original  position,  having  slid  down  the  hill  slope  in  obedience  to  the 
laws  of  gravity.  This  shattering  of  the  rock-surface  has  caused  one 
very  important  and,  in  Cripple  Creek's  case,  far-reaching  result. 
There  are  no  outcrops.  Ordinarily,  the  veins  of  gold-ore  stand 
above  the  surface  with  that  boldness  which  caused  the  Australian 
miner  to  term  them  "  reefs,"  and  the  Calif ornian  to  call  them 
"  ledges."  The  ore,  as  will  be  seen  when  discussing  the  geology  of 
the  gold-field,  is  essentially  mineralised  and  enriched  rock,  compara- 
tively devoid  of  the  quartz  composing  the  typical  lodes  of  other 
districts  in  America  or  Australia,  and  consequently  it  shares  with 
the  rock  the  tendency  to  undergo  easy  shattering.  Solid  veinstone, 
therefore,  rarely  survives  amid  the  general  disintegration,  the  out- 
crop of  the  Independence  being  a  very  notable  exception. 

The  first  discoveries  in  mining  are  usually  due  to  the  finding  of 
outcrops  ;  in  the  absence  of  them,  deep  explorations  are  rarely  under- 
taken. Deep  ravines  often  afford  good  natural  sections  of  the  rock 
formation.  The  Cripple  Creek  district  was  as  deficient  in  the  one 
feature  as  the  other.  The  absence  of  steep  declivities  and  con- 
sequent rock  faces  was  characteristic  of  the  pastoral  landscape,  and 
the  angular  debris  covering  the  rounded  hildsides  made  digging 
difficult.  For  these  reasons,  although  the  district  was  traversed  by 
many  thousands  of  prospectors  at  successive  epochs,  the  existence 
of  rich  lodes  was  not  surmised  until  a  very  recent  date,  and  many 
experienced  miners  failed  of  success  at  first  because  they  encountered 
conditions  unfamiliar  to  them.  Among  the  early  arrivals,  in  1891 
and  1892,  were  miners  from  Gilpin,  Leadville,  and  Aspen,  men  of 
knowledge  in  their  own  habitat,  but  unable  to  understand  the 
peculiar  vein  structure  which  they  saw  at  Cripple  Creek.  It  was 
the  adverse  opinion  of  these  men,  rather  than  the  views  of  geolo- 
gists or  scientific  observers,  which  injured  the  reputation  of  the 
goldfield  in  the  beginning  of  its  development. 

THE  GEOLOGY  OF  THE  GOLDFIELD. 

The  intimate  relationship  between  geological  structure  and  ore 
occurrence  has  nowhere  been  more  forcibly  emphasised  than  in 
Colorado.  This  is  largely  due  to  the  labours  of  the  United  States 


10 

Geological  Survey,  whose  monographs  on  Leadville  and  Cripple 
Creek  (particularly  the  former;  have  been  of  inestimable  assistance 
to  the  mining  industry. 

The  dissemination  of  accurate  knowledge  regarding  the  geology 
of  mining  districts  has  been  aided  by  the  increasing  simplicity  and 
clearness  of  the  language  employed  to  convey  it.  There  was  a 
time  when  geological  data  were  expressed  through  the  distorted 
medium  of  six-syllabled  words,  and  scientific  men  appeared  to  follow 
the  example  of  the  hierophants  of  the  ancient  temples,  who  spoke 
to  the  populace  only  in  language  incomprehensible  to  them.  The 
application  of  science  to  commerce,  of  geology  to  the  industry  of 
mining,  has  led  to  the  recognition  of  the  fact  that  to  talk  to  busi- 
ness men  in  a  hybrid  Greek-Latin  jargon,  is  only  an  impertinence. 
If  mining  be  not  a  business,  it  is  a  vain  delusion.  The  language 
of  technical  science  when  it  bears  upon  business  must  be  made 
intelligible  to  business  men,  otherwise  it  will  remain  a  mere  abra- 
kadabra  of  speech.* 

The  mines  of  Cripple  Creek  are  situated  in  a  complex  of  vol- 
canic rocks,  occurring  amid  the  mass  of  granite  whose  culminating 
point  is  Pike's  Peak.  These  volcanic  rocks  found  a  passage  through 
the  underlying  granite  in  the  comparatively  recent  period  known 
to  science  as  the  Miocene,  an  early  part  of  the  last  of  the  three 
great  subdivisions  of  geological  time.  The  granite  was  formed  in 
the  very  dawn  of  time,  out  of  the  substance  of  it  the  mighty  foun- 
dations of  Pike's  Peak  were  upbuilt  and  the  crest  of  the  mountain 
was  chiselled.  It  is  the  basal  rock  of  the  region  and  at  one  time 
probably  formed  the  floor  of  the  ancient  seas  which  received  the 
sediments  now  composing  the  sandstones  and  limestones  flanking 
the  Front  range.  The  granite  is  of  a  particular  type,  known, 
because  of  its  prevalence  in  this  locality,  as  the  Pike's  Peak  granite. 
It  is  coarsely  crystalline  and  its  three  ingredients,  the  minerals 
quartz,  mica,  and  felspar,  are  easily  distinguishable  by  the  unaided 
eye.  A  beautiful  red  tint,  mainly  due  to  the  colour  of  the  felspar, 
characterises  it  and  renders  it  recognizable  by  the  least  observant. 

*  I  have  in  the  present  contribution  laid  myself  open  to  the  criticism  of 
technical  men  by  avoiding  the  use  of  technical  terms  and  by  a  seemingly 
unnecessary  translation  of  those  the  use  of  which  was  unavoidable.  It  may 
seem  to  be  a  work  of  supererogation,  yet  because  an  institution  of  mining  and 
metallurgy  does  its  most  useful  work  when  it  transmits  the  recorded  observa- 
tions of  its  members  to  those  who  are  engaged  in  the  industries  the  benefit  of 
which  it  promotes,  therefore  it  seemed  better  to  me  to  give  explanations 
needless  to  scientific  men  than  to  be  unintelligible  to  those  to  whom  these 
observations  may  be  of  interest,  however  slight,  and  of  use,  however  insig- 
nificant. 


11 

Long  subsequent  to  the  formation  of  the  granite  and  the  sedi- 
mentary rocks  which  were  laid  down  upon  it,  there  began  an 
elevatory  movement  supposed  to  be  traceable  to  the  re-adjustment 
of  the  earth's  exterior  to  its  cooling  and  shrinking  interior. 
Accompanying  this  movement  there  occurred  a  general  fracturing  of 
the  rocks  thus  affected,  so  as  to  permit  volcanic  matter  to  force  a 
way  upward,  after  the  manner  of  water  rising  through  cracks  in 
the  overlying  ice.  The  volcanic  rock  thus  brought  to  the  surface 
of  the  granite  slowly  filled  the  hollows  of  its  uneven  surface,  and 
spread  over  a  large  area  since  then  diminished  by  the  patient  forces 
of  atmospheric  erosion,  which  during  the  long  period  of  time 
separating  the  Miocene  from  the  present  day,  have  slowly  sculptured 
the  hills  and  valleys  of  the  district. 

A  glance  at  the  coloured  geological  map  of  the  goldfield  exhibits 
a  great  variety  of  volcanic  rocks.  The  principal  of  these  is  ande- 
site  breccia.*  The  very  nature  of  the  breccia  suggests  the  violence 
of  the  volcanic  action  which  brought  it  to  the  surface  of  the  granite. 
The  miners  call  the  breccia  "  porphyry  "  from  its  apparent  resem- 
blance to  the  rocks  of  that  class  with  which  they  were  previously 
familiar  in  the  Leadville  and  in  the  Gilpin  County  mines.  The 
porphyry  of  Leadville  is  quartz-felsite,  that  of  Gilpin  is  quartz- 
andesite.  Porphyry!  is  an  adjective-noun  and  refers  to  the  struc- 
ture rather  than  to  the  composition  of  a  rock,  so  that  there  is 
"  granite-porphyry,"  "  diorite-porphyry,"  "  andesite-porphyry,"  &c., 
the  term  being  applied  to  rock  of  igneous  origin  in  which  particular 
minerals  are  distinguishable  amid  the  ground  mass  of  the  rock  so  as 
to  give  it  a  speckled  appearance.  The  Cripple  Creek  breccia  has 
this  appearance,  but  it  is  due  to  the  fact  that  it  is  made  up  of  a 
heterogeneous  mass  of  rock  particles  of  every  size,  from  the  most 
minute  powder  to  fragments  as  large  as  a  man's  head.  These  con- 

*  "Andesite"  is  derived  from  Andes,  the  mountain  range  where  this  rock 
is  especially  prevalent.  "Breccia"  is  a  word  of  Italian  origin,  and  means 
"  broken."  It  is  a  term  applied  to  rocks  which  are  made  up  of  fragmentary 
material. 

t  "  Porphyry  "  comes  to  us  through  the  Greek  word  porphyra,  signifying 
purple.  It  was  first  xised  to  designate  a  beautiful  rock  of  this  type  which  the 
Eoinans  obtained  from  the  quarries  of  Grebel  Dokhan,  on  the  shores  of  the  Eed 
Sea.  This  original  "porphyry"  called  by  the  Italians  " porfido  rosso  antico," 
had,  according  to  Zirkel,  a  beautiful  blood-red  ground  mass  speckled  with 
small  snow-white  and  rose-red  crystals  of  felspar.  But  the  first  meaning  of 
the  term  which  depended  on  the  colour  has  long  been  lost  in  another  meaning 
which  refers  to  the  structure.  A  rock  is  a  "  porphyry,"  or,  more  correctly, 
is  "  porphyritic,"  when  some  particular  constituent  mineral,  very  often  felspar, 
stands  out  well  defined  from  the  general  ground-mass,  as  in  the  western 
miners'  familiar  "  bird's-eye  porphyry." 


12 

sist  mainly  of  andesite,  but  the  other  rocks  are  included,  especially 
near  the  edges  of  the  volcanic  vent.  Some  of  this  material  is 
mere  volcanic  dust,  called  tuff,*  which,  when  consolidated  under 
pressure  and  cemented  by  silicious  waters,  becomes  compacted  into 
a  dense  hard  substance  difficult  to  distinguish  from  a  true  crystal- 
line rock ;  so  that  it  is  not  to  be  wondered  that  the  miners  often 
label  it  with  an  incorrect  name. 

The  breccia  lies  in  the  uneven  hollows  of  the  ancient  surface  of 
the  granite,  and  probably  fills  a  large  part  of  the  vent  through 
which  it  was  ejected.  The  thickness  of  the  breccia  has  not  been 
proved,  nor  has  the  exact  position  of  the  vent  been  discovered, 
although  there  is  evidence,  in  the  composition  of  the  rocks,  indi- 
cating the  approximate  position  of  it  to  be  just  west  of  the  town  of 
Goldfield  and  near  the  locality  covered  by  the  Hull  City  placer. 
The  mine  workings  have  shown  the  thickness  of  the  breccia  to  be 
over  a  thousand  feet  in  several  places  ;  but  as  these  are  for  the  most 
part  near  the  edge  of  the  mass  there  is  every  probability  that  the 
maximum  depth  of  this  formation  is  several  times  one  thousand  feet 
in  the  vicinity  of  the  point  of  extrusion. 

The  accompanying  sketch  of  the  Cripple  Creek  volcano  is  largely 
diagrammatic,  but  it  will  serve  to  convey  a  general  idea  of  the 
geological  structure  of  the  district. 

The  breccia  is  penetrated  and  traversed  by  later  volcanic  rocks, 
of  which  phonolitef  is  the  most  important  in  its  relation  to  the 
occurrence  of  ore.  Until  recent  years  phonolite  was  not  known  as 
a  rock  species  save  as  forming  the  Wolf  rock  in  Cornwall,  and, 
therefore,  its  association  with  great  mineral  wealth  at  Cripple  Creek 
has  been  one  of  the  most  interesting  features  of  the  development  of 
that  district.  The  phonolite  occurs  for  the  most  part  in  dykes,  that 
is  to  say,  in  approximately  vertical  sheets  which  traverse  the  older 
formations,  the  granite  and  the  breccia,  in  various  directions,  and 
are  probably  united,  at  depths  far  beyond  the  reach  of  human  ex- 
ploration, to  larger  masses  of  rock  having  a  similar  composition, 
just  as  the  cracks  in  ice  are  filled  with  a  liquid  similar  to  that 
beneath. 

These  dykes  follow  such  lines  of  weakness  in  the  older  rocks  as 

*  "  Tuff  "  comes  from  the  Italian  tufa.  Vesuvius  is  responsible  for  the 
Italian  nomenclature  of  many  volcanic  products. 

f  "  Phonolite  "  is  derived  from  two  Greek  words,  phone,  signifying  sound, 
and  lithos,  meaning  stone.  It  owes  this  name  to  the  fact  that  it  rings  when 
struck  by  a  hammer.  This  is  due  to  its  hardness  and  close  texture.  It  is  also 
called  "  clinkstone."  The  essential  constituents  of  phonolite  are  nepheline  and 
the  glassy  variety  of  felspar  termed  sanidine. 


13 

were  developed  [into  fractures  during  those  periods  when  the  rocks 
underwent  strains,  the  latter  being  considered  to  be  the  result  of 
the  slow  wrinkling  of  the  earth's  crust  due  to  its  readjustment  over 


C  f? 


FIG.  1. 


PLAN 


a  cooling  and  shrinking  interior.  The  phonolite  rose  in  a  mobile,  if 
not  molten,  condition  through  the  fractures  thus  formed  after  the 
manner  of  water  rising  through  the  cracks  in  [the  overlying  ice. 
The  structural  conditions  thus  created  gave  a  direction  to  the  sub- 
sequent circulation  of  underground  waters.  The  deposition  of  ore 


14 

is  the  result  of  such  circulation,  the  mineral-bearing  solutions  being 
the  vehicle  by  which  the  metals  are  leached  out  of  the  rocks  and 
laid  down  elsewhere  in  such  a  concentrated  form  and  within  such  a 
distance  of  the  surface  as  to  render  them  valuable  to  man.  The  place 
of  origin  is  surmised,  but  vaguely,  as  being  deeper  than  our  deepest 
mines,  and  the  place  of  deposition  is  not  always  the  place  where  the 
miner  finds  it.  Lines  of  weakness,  healed  and  strengthened  by  the 
cementing  effects  of  hot  igneous  rock,  in  the  form  of  dykes,  afford 
new  lines  of  lesser  resistance,  parallel  to  the  old  ones  and  along  the 
contact  of  the  two  rocks  of  unlike  hardness  and  texture.  For  this 
reason  ore-bearing  veins  so  often  accompany  dykes.  They  do  so  at 
Cripple  Creek. 

Before  venturing  upon  the  details  of  vein  structure  in  this  par- 
ticular district,  it  will  be  well  to  preface  such  a  description  by  a 
few  general  remarks  upon  the  subject  as  viewed  from  a  wider 
standpoint. 

The  mines  of  Cripple  Creek  afford  excellent  illustrations  of  the 
teachings  of  modern  geology,  and  emphasise  the  incorrectness  of 
the  hasty  generalisations  of  Sandberger  and  others  before  him.  It 
is,  of  course,  foolish  to  deride  even  theories  which  are  now  laid  on 
the  shelf,  after  they  have  served  the  purpose  of  quickening  the 
researches  of  scientific  enquirers.  A  working  theory  is  needed  in 
order  to  give  some  sort  of  direction  to  observation,  because  without 
an  intelligent  idea  of  what  may  be  the  possible  fact  one  certainly  will 
be  unlikely  to  discover  the  real  one.  A  man  who  is  lost  on  a  dark 
night,  and  declines  the  guidance  of  a  tallow  candle  because  it  is  too 
poor  a  light  to  illuminate  the  mountains  in  the  distance,  will  lose 
the  opportunity  of  avoiding  the  holes  at  his  feet.  The  exploded 
ideas  of  Werner  served  a  good  purpose  in  their  own  day,  because  the 
accumulation  of  observations  intended  to  disprove  them  became  at 
the  same  time  the  basis  for  other  views,  which  were  as  much  nearer 
the  truth  as  the  data  on  which  they  in  turn  were  founded,  were 
more  complete  and  more  thorough.  During  later  years  the  lateral 
secretion  theory  of  Sandberger  became  accepted  by  certain  dis- 
tinguished geologists,  and  was  as  vigorously  combated  by  others, 
notably  Posepny,  with  the  result  that  a  great  impetus  was  given  to 
observation,  and  a  large  mass  of  new  facts  has  been  collected, 
bringing  the  scientific  explanations  of  ore  occurrence  another  step 
nearer  the  knowledge  of  things  as  they  are.  The  unthinking  sneer  at 
the  faltering  steps  of  science,  and  the  working  miner  is  apt  to  belittle 
the  aid  which  geology  gives  him.  The  amount  of  accurate  knowledge 
of  any  kind  so  far  attained  by  the  human  race  is  small  when  com- 
pared to  the  bulky  mass  of  that  which  they  think  they  know,  Each 


15 

intelligent  observation  is  one  step  nearer  the  attainment  of  truth, 
and  those  who  direct  the  working  of  mines  will  get  more  aid  from 
geology  when  they  contribute  the  necessary  data  without  which  the 
occurrence  of  ore  will  remain  merely  a  maze  of  tangled  phenomena. 

It  is  well  to  begin  a  discussion  of  a  subject  by  defining  the  terms 
employed.  A  "  lode  "  is  something  that  leads  a  miner,  the  words 
"  lode  "  and  "  lead  "  having  an  identical  Saxon  origin.  Australian 
miners  designate  a  small  continuous  vein  connecting  larger  ore- 
bodies  as  a  "leader."  "Lode  "is  therefore  a  comprehensive  term 
covering  many  diverse  forms  of  ore  occurrence.  The  word  "  vein  " 
has  a  more  restricted  usage,  and  describes  those  lodes  in  which  the 
ore  is  supposed  to  occur  in  a  tabular  form,  occupying  continuous 
planes  which  are  approximately  vertical,  and  traverse  the  rocks  like 
interminable  sheets  of  paper  set  on  edge,  that  is,  they  are  supposed 
to  fill  simple  fractures  made  in  a  perfectly  homogeneous  material. 
The  term  was  originally  borrowed  from  the  human  anatomy,  and 
the  oldest  writers  have  used  the  simile  of  the  rock  veined  with 
the  precious  metal.  Nature  does  not  recognise  the  definitions  of 
the  technical  dictionary  and  in  mining  practice  it  has  been 
found  that  regularity  of  structure  is  the  exception  rather  than  the 
rule.  The  geologist  of  50  years  ago,  when  the  science  was  more 
the  product  of  the  library  and  the  laboratory  than  of  actual  obser- 
vation underground,  conceived  the  ore  as  having  filled  gaping 
fissures  in  the  rock,  comparable  to  the  crevasses  of  a  glacier,  and 
\vhen  he  had  noted  the  dissimilarity  between  the  ore  and  the 
encasing  rock,  he  imagined  the  former  to  have  been  due  to  an  up- 
vvelling  of  molten  metallic  matter.  The  ideas  of  the  present  day 
are  still  slightly  tainted  by  the  imaginations  of  the  past  and  the 
terms  of  an  obsolete  philosophy  continue  to  cling  to  our  nomen- 
clature.* 

Modern  investigations,  based  on  accurate  chemical  knowledge,  as 
.veil  as  geological  observation,  have  all  gone  to  prove  that  gold  ores  are 
not  the  product  of  direct  volcanic  action,  but  that  they  have  been 
con  seyed  to  the  place  where  the  miner  finds  them  through  the 
medium  of  water,  the  metals  having  been  dissolved,  in  various 
chemical  combinations,  by  underground  solutions,  and  precipitated 
along  those  fractures  in  the  rocks  which  have  been  first  lines  of  least 
resistance,  and  then  lines  of  maximum  circulation.  The  mineral 
solutions  cannot  have  come  from  indefinite  depths,  because  the 

*  Thus  the  terms  "  fissure- vein,"  ''vein-filling,"  "vein-walls,"  &c.,  carrv 
with  them  suggestions  which  are  misleading  to  untechnical  persons,  and  are 
the  heritage  of  ideas  now,  I  trust,  recognised  as  untenable  in  the  light  of  later 
evidence. 


16 

increase  of  heat  (1°  F.  for  every  48  ft.  of  descent)  observable  in  the 
sinking  of  shafts  and  boreholes  indicates  that  at  a  horizon  of  about 
20,000  ft.  below  the  present  surface  water  would  become  dissociated* 
into  its  constituent  gases.  It  is  considered  probable,  from  the 
evidence  yielded  by  certain  classes  of  lodes,  particularly  those  of 
nickel  ores,t  that  volcanic  action  serves  to  bring  the  metals  from 
these  great  depths  to  that  zone  of  the  earth's  exterior  wherein 
solvent  waters  can  circulate.  The  experience  of  gold  mining  corro- 
borates this  view,  the  association  of  volcanic  rocks  with  bodies  of 
valuable  ore  having  become  almost  proverbial. 

It  is  not  surprising,  therefore,  that  this  very  fact  has  tended  to 
cause  a  confusion  of  ideas  between  volcanic  action  and  lode  forma- 
tion. 

In  a  railway  cutting  between  the  towns  of  Cripple  Creek  and 
Anacoda,  there  is  a  bit  of  nature's  testimony  which  will  be  of  service 
in  getting  a  clear  idea  of  the  essential  characteristics  of  gold-bearing 
veins  as  compared  with  dykes  of  volcanic  rock.  The  accompanying 
drawings  will  help  the  description.  In  Fig.  2  there  is  afforded  an 
excellent  illustration  of  simple  dyke  structure.  The  dyke  in  this 
case  is  composed  of  basalt ;  it  is  from  9  to  15  in.  in  width,  and  can 
be  easily  traced  as  an  irregular  dark  band  traversing  the  coarse- 
grained pink  granite.  The  dyke  is  very  well  defined,  exhibiting 
clean-cut  lines  of  demarcation  from  the  enclosing  granite,  and  it  is 
evident  from  the  contour  of  the  walls  that  it  occupies  a  fault  fissure. 
The  outline  of  the  east  wall  corresponds  exactly  to  that  of  the 
western  one,  the  movement  of  the  latter  having  been  upward, 
causing  a  displacement  equal  to  about  14  in.  It  is  a  clean-cut 
fissure  in  the  granite,  filled  with  foreign  material,  a  basic  volcanic 
rock,  which  probably  welled  upward  in  a  mobile  condition,  filling 
the  fissure  as  it  was  formed,  so  as  at  no  time  to  permit  of  a  vacuity. 
Compare  this  with  Fig.  3,  which  is  a  sketch  of  a  gold-bearing  vein, 
situated  at  a  distance  of  a  few  yards  from  the  dyke  illustrated  in 
Fig.  2.  The  country  is  the  same,  viz.,  granite,  but  in  this  instance 
the  vein  filling  is  not  foreign  matter,  but  essentially  rock  in  place ; 
it  is  granite,  altered,  indeed,  but  easily  recognisable,  in  spite  of  the 
kaolinisation  of  the  felspar,  and  the  partial  removal  of  the  mica. 
There  are  no  clearly  defined  boundaries  between  the  decomposed 
vein  matter  and  the  enclosing  country,  nor  is  there  any  evidence  of 
faulting.  The  lines  of  fracture  shown  in  the  granite  are  the  joints 
of  that  rock,  and  those  which  are  observable  in  the  vein  itself  are 

*  I  refer  to  the  critical  point,  which  is  773°  F.     At  this  temperature  water 
cannot,  however  great  the  pressure,  retain  its  liquid  form. 
f  As  indicated  by  the  researches  of  J.  H.  L.  Yogt. 


17 

not  continuous,  but   rather  a   closely  knit  series  of  little  breaks, 
which  have  afforded  a  passage  for  a  liquid  more  subtle  than  the 

FIG.  2. 


H  'I  FOOT 


A*A    BASALT  V 


GRANITE. 


basalt.  The  vein  occupies  a  line  of  maximum  porosity  along  which 
water,  more  searching  than  any  molten  lava,  has  found  a  way, 
decomposing  the  soluble  ingredients  of  the  rock,  and  depositing  a 


18 


minute  quantity  of  gold,  insufficient  to  make  the  decomposed 
granite  of  the  vein  differ  essentially  from  the  outer  country,  but 
rendering  one  gold-bearing  ore,  and  leaving  the  other  barren  rock. 


FIG.  3. 


lUt^fbr" 


Here  we  have  a  dyke  compared  with  a  vein  and  volcanic  agencies 
brought  into  strong  contrast  with  aqueous  action.     The  faulting 


19 

along  the  fissure  followed  by  the  dyke  is  easily  seen,  but  no 
evidences  of  such  movement  can  be  discerned  along  the  seam  of 
altered  granite,  which  forms  the  gold  vein.  Nevertheless  there 
must  have  been  some  movement,  however  slight,  because  a  crack 
or  break  is  not  made  evident,  can  be  considered  only  as  latent, 
until  the  two  faces  of  it  are  caused,  by  that  very  shifting,  so  to 
disagree  as  to  produce  the  irregularities  which,  when  linked  together, 
form  the  visible  line  of  fracture.  Even  the  joints  in  the  solid  granite 
require  such  [an  explanation,  and  however  insignificant  the  shifting 
may  be,  it  marks  the  adjustment  of  the  rock  to  the  effects  of  stresses, 
traceable  in  this  case  to  the  volcanic  energies  which  extruded  the 
large  masses  of  breccia  forming  the  characteristic  feature  of  the 
geology  of  Cripple  Creek.  Permit  me  to  repeat,  however  insig- 
nificant this  shifting  may  have  been,  it  made  the  rocks  pervious  to 
underground  mineral-bearing  solutions,  and  where  it  occurred  it 
developed  a  series  of  united  passages,  which  afforded  a  line  of  maxi- 
mum porosity,  permitting  of  the  circulation  of  gold-bearing  waters, 
and  the  subsequent  precipitation  of  the  metal  dissolved  in  them. 

The  Cripple  Creek  district  exhibits  a  great  variety  of  vein  struc- 
ture, and  in  order  to  afford  a  general  idea  of  the  conditions  under 
which  the  ore  is  found  it  will  be  necessary  to  select  one  or  two 
typical  examples.  Many  of  the  veins  are  essentially  mineralised 
dykes,  that  is,  a  part,  or  even  occasionally  the  whole  width  of  the 
dyke,  is  sufficiently  rich  to  be  regarded  as  pay  ore,  and  the  boun- 
daries of  the  dyke  then  become  the  walls  of  the  lode.  The  Moose 
vein  will  exemplify  this  type.  The  accompanying  sketch,  Fig.  4,  was 
made  at  the  350-ft.  level.  From  D  to  F  is  the  width  of  the  dyke, 
which  in  this  case  is  nepheline  basalt.  It  traverses  the  andesite 
breccia,  which  is  indicated  at  AA.  The  pay  ore  extends  from  E  to 
F,  a  width  of  10  in.,  and  it  is  distinguished  from  the  remainder, 
EG,  comparatively  barren  portion  of  the  dyke,  a  dark  bluish  grey 
rock,  by  being  iron  stained  and  seamed  with  reddish  brown  threads 
in  which  gold  and  tellurides  occur.  The  multiple  fracturing,  parallel 
to  the  walls  of  the  dyke,  is  a  characteristic  feature  of  such  lodes, 
and  experience  has  shown  that  there  is  reason  to  expect  the  lode  to 
consist  of  rich  ore  when  it  becomes  threaded  with  minute  seams 
following  these  lines  of  fracture.  This  feature  can  be  described  as 
a  sheeting  of  the  rock ;  it  is  a  very  important  factor  in  ore  depo- 
sition. 

Another  type  is  presented  by  those  veins  which  accompany  the 
phonolite  dykes.  This  is  very  characteristic  of  the  Cripple  Creek 
district.  The  direction  followed  by  a  majority  of  the  veins,  espe- 
cially on  Battle  Mountain  and  Bull  Hill,  conforms  to  that  of  a 

c  2 


20 

system  of  phonolite  dykes.  While  a  particular  vein  may  not  adhere 
continuously  to  the  line  of  the  dyke  with  which  it  is  associated, 
nor  the  ore  itself  be  found  in  the  substance  of  the  dyke,  when  they 


FIG.  4. 


ANDESITE  BRECCIA      [OfJ  NcPHELINE  BASALT 


VEIN   MATTER 


are  together,  yet  the  behaviour  of  the  vein  is  intimately  connected 
with  that  of  the  dyke,  and  the  ore  occurrence  is  modified  by  both. 
The  accompanying  sketch,  Fig.  5,  recently  made  in  the  Independence 
Mine,  will  illustrate  this.  The  lode  AB  is  shown  to  be  in  breccia, 
and  follows  a  phonolite  dyke,  BC,  which  is  2  ft.  wide.  The  ore  is 
confined  to  the  breccia,  and  if  the  phonolite  is  enriched  it  is  so  to  a 
slight  extent  only,  and  the  enrichment  is  confined  to  the  planes  of 


21 

fracture  near  the  lode  and  does  not  extend  into  the  body  of  the  dyke. 
The  ore  is  essentially  andesite  breccia,  rendered  gold-bearing  by  the 


FIG.  5. 


PHONO  LITE: 


22 

penetration  of  solutions  which  have  circulated  along  the  line  of 
contact  between  the  phonolite  and  the  breccia.  The  gold  occurs  not 
only  in  the  seams  which  follow  the  fracture  in  the  breccia,  but  it  is 
also  found  in  the  heart  of  it,  where  a  spongy  vesicular  appearance 
has  been  caused  by  the  removal  of  the  more  soluble  ingredients  of 
the  rock. 

In  striking  contrast  to  the  two  types  above  described  I  would 
instance  those  veins  which  are  neither  mineralised  dykes  nor  imme- 
diately* associated  with  them,  but  consist  essentially  of  lines  of 
fracture  in  the  body  of  the  granite  itself.  A  very  good  illustra- 
tion is  afforded  by  the  Independence  vein  when  it  leaves  the  breccia 
and  extends  southward  into  the  granite  of  the  Washington  claim. 
The  accompanying  drawing,  Fig.  6,  was  made  at  the  bottom  of  the 
old  whim  shaft  on  the  100-ft.  level.  The  lode  is  essentially  decom- 
posed granite  divided  into  two  equal  portions  of  2  ft.  each  on  either 
side  of  the  small  seam  EF,  which  consists  of  a  parting,  E,  marked 
by  a  slight  clay  selvage,  and  a  seam  of  quartz,  F,  which  is  only 
from  J  in.  to  \  in.  thick,  but  very  regular  and  continuous.  The 
lode,  which  here  consists  of  4  ft.  of  2  oz.  ore,  has  no  walls,  that  is 
to  say,  the  decomposed  gold-bearing  granite,  CD,  is  not  separated 
from  the  undecomposed  valueless  granite,  A  and  B,  by  any  clearly 
defined  boundary,  although  the  transition  from  the  dark  brownish 
granite  into  the  fresh  pink  rock  can  be  clearly  followed  by  looking 
at  it  from  a  distance  of  5  or  6  ft.  The  ore  is  therefore  essentially 
gold-bearing  granite,  which,  if  examined,  will  be  found  to  have 
undergone  several  changes,  the  most  notable  being  the  removal  of 
the  mica,  the  decomposition  of  the  felspar,  and  the  addition  of 
secondary  quartz  ;  the  general  effect  being  to  give  it  a  honeycombed 
spongy  character. 

The  lode  above  described  is  similar  to  the  outcrop  which  so  many 
overlooked  in  1890  and  1891,  because  it  carried  no  visible  metallic 
minerals  or  free  quartz.  It  will  be  of  interest  to  examine  the 
famous  outcrop  more  closely.  The  reef  has  evidently  undergone  a 
weathering,  yet  it  has  withstood  the  elements,  because  it  carries 
more  quartz  than  the  surrounding  rock.  The  outcrop  ceases  to 
appear  at  a  point  now  occupied  by  the  No.  1  shaft  of  the  Inde- 
pendence Mine.  This  shaft  is  situated  at  the  contact  of  the  granite 
and  the  breccia.  The  lode  continues  northward  for  a  great  distance, 
as  the  subterranean  workings  testify.  Southward  the  lode  is 
encased  in  granite,  and  it  is  itself  composed  of  granite.  The  barren 
outer  rock  is  pink  in  colour,  and  its  constituent  minerals  present  a 

*  Emphasis  is  laid  on  "  immediately  "  because  the  Independence  vein,  for  a 
large  part  of  its  known  course,  accompanies  a  phonolite  dyke. 


23 

fresh  unaltered  appearance.  The  gold-bearing  portion,  comprised 
within  the  lode,  has  a  dull  brown  tinge ;  it  is  noticeable  that  the 
mica  is  absent,  having  evidently  been  leached  out,  leaving  patches 
of  chlorite  and  iron-stained  spots  in  which  free  gold  can  occasionally 


FIG.  6. 


.-  4  •:  4 . 


'.  --.    4-    +  . 
-K  ..+ 

* 


t  t 

+ 
-T44 


•-,%          -V\        '«  ^/-      '•..".*..       •/         -4-T 


.       4-4      +    +  - 

4-  ./  +  .4-  +    +  +  + 

•  N.  vf..4       •+-    4-     4 


••4.  4-  4  -4.  -4  '.  :•  •:.  .  js+-  •     :   tf  •  •'..-.  v1  -     ,    •' 

4.    -4-     -i     -4  1-.  •-+-'.  **><1"  •    •'    '    •'  1  f.  '.-\  '4  '  *  '. 
4   4-    4    -4   4-    .       /.-/:  vT'.        *.-•     •'..  tT-. 

v^li^S  1^?!  ?  ifr^vv. 

^^IKf  Itifell  w^ 

4    4     4    4     -  '      -     V.  V   '  *-"A.flX   /    '    '   ••  V'  '   -.-I-         '    f-    4-    t    t   -1 
444    4\'.  •+  v-       .  V  --'I         •       '  -      '  V   ••••>^-       '^    4  <-     4     4    4    -h 

:*>.-*.-*.Vrv>>  +.->sH-:.J.  •  ::/:t  :^::.-j>^  +  4  +  ^ 


4444  *.  "T  V         •    X''-'l   '      '          •     '    J.'    •  l!>>^  ....•*    4  «•+•     1 

4    4    -+    4\'..>V   +..XX't'    ..•.'.«    •'    V-f   .-x^'.  '.  •^>-+-       4.     H      +4* 

+^  -*+'.*i:  x  4  •  v*/  +  .i'--'-'\i>-  ••  +"       '.%  4  +  4  4 

^vJ-^  f  Mf;v^^;  .>»y 

4.   4  4-4      *'+•.•.       ••        fx  IA.%     ••••./•»•'  f-  -I  .->f     4      -f-      •>- 

.4  4.  ^  4  .  -  -  ;:W  -  .  .   ;     fl*,/v>  '     ••;'     •  :<<*  •*•   *     t     T  ^ 

^ 4  \"V^-i:V:-i'.  *-'''-ii"''[  •-  ^.    *•  i^ •1~4. w^ 

AC  *F  "h  •*•         >i1t 


OR 


LODE 


24 

be  distinguished ;  of  the  two  felspars*  of  the  original  rock  the  more 
soluble  has  become  kaolinised,  while  the  other  remains  so  undecom- 
posed  as  to  preserve  much  of  the  usual  appearance  of  the  granite  ; 
the  original  quartz  has  been  removed,  probably  by  the  action  of  the 
hydrofluoric  acid,  the  presence  of  which  at  one  time  is  strongly 
suggested  by  the  purple  fluorite  now  staining  portions  of  the  ore ; 
further,  there  is  abundant  secondary  quartz,  in  groups  of  opalescent, 
indistinct  crystals,  to  the  presence  of  which  the  lode  owes  the  fact 
that  it  is  harder  than  the  enclosing  granite. 

When  the  lode  penetrates  the  breccia  it  continues  to  be  made  up, 
not  of  free  quartz  or  any  other  foreign  vein-matter,  but  of  the 
formation  which  it  traverses,  so  that  south  of  the  contact  the  Inde- 
pendence is  essentially  gold-bearing  granite,  and  north  of  the  contact 
it  is  gold-bearing  andesite  breccia.  Why  there  is  no  outcrop  north 
of  the  contact  I  do  not  know,  unless  it  be  that  the  lode  partakes  of 
the  fissile  and  easily  eroded  character  of  the  breccia,  and  has  not 
been  strengthened  by  the  infiltration  of  sufficient  additional  secondary 
quartz  to  enable  it  to  withstand  the  obliterating  hand  of  time. 

The  character  of  this  lode  presents  several  notable  features,  a  high 
value  from  a  commercial  standpoint  coinciding  with  peculiar 
scientific  interest.  At  the  third  level  there  is  presented  a  good  idea 
of  the  general  relation  existing  between  the  gold-bearing  portion, 
recognised  as  "  the  lode,"  and  the  rock  formations  which  it  traverses. 
It  is  remarkable  that  while  the  several  bands  of  gold-bearing  matter 
have  a  general  parallelism  and  sympathy  with  the  course  of  the 
two  phonolite  dykes,  yet  a  large  part  of  the  ore  is  not  contiguous  to 
the  phonolite,  but  traverses  the  granite  and  the  breccia,  regardless 
of  such  structural  features  as  the  contact  or  the  dykes  themselves. 
The  ore  has  no  defined  walls ;  when  definite  partings  appear  to 
limit  the  widths  of  gold-bearing  material  it  is  only  to  mislead  ;  there 
are  similar  "  walls  "  both  within  the  ore  itself  and  beyond  it  in  the 
outer  country.  When  the  ore  abuts  against  a  phonolite  dyke  it 
does  not  usually  extend  into  the  dyke,  save  occasionally  where 
tellurides  are  found  upon  the  cleavage  planes  of  the  latter  near 
its  edges.  Where  the  lode  crosses  the  contact  the  ore  changes  at 
once  from  gold-bearing  granite  to  gold-bearing  breccia.  A  widen- 
ing of  the  ore-body  exists  at  the  contact,  and  for  a  considerable 
distance  both  north  and  south  of  it.  The  composition  of  the  rocks 
appears  to  have  been  an  entirely  unimportant  factor  as  compared  to 
the  physical  and  structural  conditions  in  the  locality  of  the  ore 
deposit.  The  evidence  warrants  the  most  careful  study,  and  would 

*  Orthoclase  and  oligoclase.  The  plagioclase  variety,  containing  a  larger 
percentage  of  lime,  is  the  one  which  has  undergone  decomposition. 


25 

furnish  the  text  for  a  long  discussion  of  the  essential  features  of  ore 
deposition.  Few  examples  of  lode  structure  so  well  emphasise  the 
general  truth  of  those  modern  ideas  of  ore  deposition  which  are 
advocated  by  the  teachings  of  Posepny.  It  is  interesting  to 
accentuate  this  fact,  because  there  was  an  erroneous  impression 
conveyed,  in  the  early  days  of  Cripple  Creek,  by  the  writers  of  the 
daily  press,  that  the  gold-field  set  at  naught  the  accepted  teachings 
of  geological  science.  The  idea  was  due  to  the  careless  utterances 
of  local  men,  and  never  emanated  from  any  recognised  authorities. 
The  converse  is  true,  and  should  be  emphasised,  namely,  no  modern 
mining  region  so  clearly  establishes  that  explanation  of  ore  deposi- 
tion, which  is  based  upon  the  recognition  of  the  laws  governing  the 
circulation  of  underground  waters,  under  conditions  traceable  to  the 
geological  structure  of  the  rocks. 

THE  ORES  AND  MINERALS. 

In  discussing  the  geological  features  of  the  district,  frequent 
emphasis  has  been  laid  upon  the  fact,  that  the  ore  is  usually  only 
rock,  whether  granite,  phonolite,  or  breccia,  which  has  become  im- 
pregnated with  gold-bearing  minerals  to  a  slight  extent  as  regards 
percentage,  but  to  a  notable  degree  as  regards  commercial  value. 
In  1893,  when  W.  S.  Stratton,  the  owner  of  the  Independence,  sent 
several  carloads  of  rich  ore  from  his  mine  to  the  Denver  smelters, 
the  officials  at  the  works  thought  a  blunder  had  been  made  and 
that  loads  of  ballast  had  been  inadvertently  consigned  to  them. 
The  ore  was  obviously  granite  and  it  required  a*  trained  eye,  such 
as  that  of  Dr.  Richard  Pearce,  manager  of  the  Boston  and  Colorado 
Smelting  Company,  to  detect  the  fact  that  the  mica  of  the  granite 
had  been  largely  removed,  leaving  small,  iron-stained  spots  amid 
which  there  were  disseminated  dull  yellow  specks  of  gold.  A 
glance  into  the  ore-bins  of  the  chlorination  establishments  will 
exhibit  a  mixture  of  broken  rock,  which  looks  more  like  the  spoil 
of  a  barren  cross-cut  than  the  yield  of  a  rich  stope.  The  petro- 
grapher,  in  looking  over  this  material,  could  easily  label  the  rock, 
and  if  not  initiated,  he  would  wonder  whether  it  could  be  gold- 
bearing.  On  being  assured  that  it  was  valuable  as  such,  he  would 
take  a  few  pieces,  and  break  them  open  so  as  to  examine  a  fresh 
surface,  and  it  would  not  be  long  before  he  would  see  on  the  planes 
of  fracture,  evidences  of  richness. 

The  gold  occurs  either  in  the  native  condition  or  as  a  telluride, 
and  is  found  distributed  among  the  interstices  of  the  rock,  lining 
the  fractures  or  penetrating  the  substance  of  it  in  threads  of  vary- 


26 

ing  minuteness.  In  lodes  traversing  the  granite,  the  gold,  or  the 
tellurides  containing  it,  will  be  scattered  amid  the  porous  cavities 
due  to  the  removal  of  certain  more  soluble  portions  of  the  rock ; 
in  phonolite,  the  values  will  be  found  more  frequently  along 
fractures  than  in  the  heart  of  it.  This  renders  the  last  mentioned 
class  of  ore  very  difficult  of  estimation.  In  the  andesite  breccia, 
the  component  fragments  of  which  are  so  heterogeneous,  the  physi- 
cal character  of  the  rock  varies  considerably,  and  the  gold  values 
will  partake  of  an  irregular  sporadic  distribution. 

The  distinguishing  feature  of  the  ores  of  the  district,  is  the 
occurrence  of  tellurides.  The  discoveries  of  these  uncommon 
minerals,  produced  nearly  as  many  misconceptions  a  few  years  ago 
as  the  finding  of  similar  minerals  at  Kalgoorlie  in  West  Australia 
Tellurides  seemed  to  create  as  much  confusion  among  the  miners  of 
both  countries,  and  to  be  as  puzzling  as  the  finding  of  the  Ornith- 
orhyncus paradoxus  (or  duckbilled  Platypus)  to  the  naturalists  at 
the  beginning  of  this  century.  Colorado,  however,  was  better 
prepared  for  the  telluride  discoveries  of  Cripple  Creek,  than 
Australia  was  to  exploit  those  of  Kalgoorlie.  The  latter  were 
unprecedented,  the  former  only  followed  the  line  of  previous,  partly 
forgotten,  experiences  in  the  Boulder  and  La  Plata  districts  of  the 
same  State. 

A  few  general  notes  concerning  the  composition  of  these  com- 
plex ores  will  be  of  interest.  And  first  a  few  definitions  are 
necessary.  The  "  tellurides "  are  compounds  of  tellurium  with 
certain  metals,  and  they  are  so  termed  just  as  the  compounds  of 
sulphur  are  called  "  sulphides  " ;  thus,  for  example,  calaverite  is 
the  telluride  of  gold,  while  iron  pyrites  is  the  sulphide  of  iron. 
The  name  "  tellurium  "  is  derived  from  the  Latin  tellus,  meaning 
the  earth,  and  was  chosen  in  opposition  to  that  of  the  element 
selenium,  which  comes  from  the  Greek  word,  selene,  the  moon. 
Tellurium  is  a  non-metallic  element  with  a  metallic  lustre,  it  acts 
as  an  acid  base,  just  as  selenium  and  sulphur  :  the  three  forming  a 
recognized  chemical  group  having  common  affinities.  If  tellurium 
were  a  metal,  as  is  often  supposed,  its  combination  with  gold  or 
silver  would  only  be  possible  as  an  alloy. 

It  is  usually  assumed  that  the  precious  metals  enter  into  the 
composition  of  tellurides,  and  a  high  commercial  value  is  taken  for 
granted  in  speaking  of  this  species  of  minerals.  Nevertheless, 
there  are  many  varieties  which  are  valueless  to  the  gold  miner,  such 
as  the  telluride  of  mercury,  called  Coloradoite,  which  occurs  at 
Kalgoorlie,  as  well  as  at  Magnolia  in  Boulder  County,  Colorado ; 
there  are  also  the  telluride  of  bismuth,  called  Tetradymite,  and  the 


27 

telluride  of  lead,  called  Altaite,  and  the  telluride  of  nickel, 
Melonite,  all  of  them  found  occasionally  in  the  mines  of  Boulder 
Comity,  as  well  as  in  the  ancient  mining  region  of  Transylvania, 
where  most  of  them  were  first  recognised.  These  tellurides  of  the 
baser  metals  occur,  for  the  most  part,  in  quantities  so  restricted  as 
to  have  no  commercial  value  and  are  rather  to  be  considered  as 
curiosities  much  desired  by  the  mineral  collector. 

In  the  mining  camps  it  is  a  frequent  custom  to  speak  of  tellurium 
when  it  is  intended  to  refer  not  to  that  element,  but  to  its  com- 
pounds with  gold  or  silver.  Tellurium  itself  occurs  native,  that 
is,  in  a  free  state,  just  as  gold,  silver  or  copper.  It  is  tin-white  in 
colour,  it  is  soft  but  brittle,  and  is  usually  found  in  a  granular 
massive  condition.  A  commercial  value  of  $3*50  per  ounce  is  ordi- 
narily quoted  for  tellurium,  but  the  demand  for  this  rare  earth  (as 
the  chemist  terms  it)  is  very  slight,  and  a  few  shipments  of  it  would 
quickly  demoralize  the  market.  No  native  tellurium  has  yet  been 
found  in  the  Cripple  Creek  district,  but  in  Boulder  County,  90 
miles  further  north,  it  occurs  among  gold  ores  in  a  free  state,  and  a 
mass  weighing  25  Ib.  was  found  in  the  John  Jay  Mine  about  twenty 
years  ago. 

Certain  telluride  materials  very  much  resemble  the  common  ores 
of  silver,  the  sulphide  of  silver  (called  argentite),  for  example,  is 
difficult  to  distinguish  from  hessite,  the  telluride  of  the  same  metal, 
silver.  The  instance  is  quoted  in  order  to  refer  to  a  simple  test 
applicable  to  any  doubtful  cases.  Remove  a  small  bit  of  the  sus- 
pected mineral  with  the  point  of  an  old  knife,  and  put  it  in  a  porce- 
lain dish  or  a  white  saucer.  Add  three  or  four  drops  of  strong  sul- 
phuric acid,  and  heat  over  a  lamp.  Should  tellurium  enter  into  the 
composition  of  the  suspected  mineral,  a  beautiful  purple  will  suffuse 
the  colourless  acid.  The  miner's  time-honoured  test  is  to  put  the 
ore  in  the  fire  of  a  blacksmith's  forge  and  roast  it.  Tellurium  fuses 
at  a  comparatively  low  temperature,  and  becomes  volatilised,  passing 
off  in  white  fumes  of  telluric  oxide.  If  the  telluride  mineral  con- 
tains gold,  the  latter  will  remain  in  the  form  of  globules.  Even 
the  precious  telluride  hidden  in  the  seams  of  the  piece  of  ore  will  be 
exuded  as  a  yellow  perspiration.  The  miner  calls  this  process 
"  sweating,"  and  the  reason  for  it  becomes  obvious  when  the  results 
are  observed. 

Experienced  miners,  such  as  those  of  the  Boulder  district  of 
Colorado,  who  have  been  working  amid  these  particular  ores  for 
twenty-five  years,  know  very  well,  from  the  disappointing  returns 
of  many  a  shipment  to  the  smelter,  that  there  are  several  minerals 
closely  resembling  tellurides  which  are  not  rich  in  gold,  and  there- 


28 

fore  that  a  rough  test,  by  roasting,  is  occasionally  necessary.  The 
mineral  may  go  off  in  fumes  when  heated,  leaving  no  gold  or  silver 
behind,  as  native  tellurium  does.  Consequently,  the  Boulder  miners 
are  apt  to  call  everything  native  tellurium  which  in  the  process  of 
roasting  disappears  entirely  or  leaves  a  residue  in  which  the  precious 
metals  are  not  recognisable.  But  among  the  latter  would  be  in- 
cluded the  tellurides  of  lead,  bismuth,  and  nickel ;  and  to  the  former 
belongs  not  native  tellurium  alone,  but  also  the  telluride  of  mercury, 
because  mercury  also  readily  volatilises  under  the  conditions  of  the 
roasting  test.  This  mistake  was  made  at  Kalgoorlie,  where  I  found 
the  telluride  of  mercury  being  labelled  "  black  tellurium,"  for  the 
reason  just  referred  to.  The  mineral  combination  of  tellurium  and 
mercury  is  rare ;  it  was  first  found  at  the  Mountain  Lion  mine  at 
Magnolia,  in  Boulder  County,  and  a  simple  test  for  it  is  to  roast  a 
particle  of  it  in  a  glass  tube.  The  mercury  is  volatilised  at  the  hot 
lower  end  of  the  tube,  and  is  condensed  at  the  cool  upper  end  in  the 
form  of  minute  metallic  globules,  which  are  readily  recognisable  as 
quicksilver. 

The  principal  telluride  minerals  found  in  the  Cripple  Creek  ores 
are  sylvanite,  calaverite,  and  petzite.  Sylvanite,  named  after  the 
place  of  its  discovery,  the  historic  goldfield  of  Transylvania,  is  the 
most  characteristic  of  Cripple  Creek  ores,  very  beautiful  specimens 
of  it  having  been  obtained  at,  among  others,  the  Independence, 
Portland,  Moon,  Anchor,  and  Anchoria-L eland  Mines.  It  is  a  double 
telluride,  containing  gold  and  silver,  an  average  composition  being 
28  per  cent,  gold,  16  per  cent,  silver,  and  56  per  cent,  tellurium. 
Sylvanite  is  a  brilliant  silvery -white  mineral,  having  a  characteristic 
crystalline  habit,  to  which  it  owes  its  other  name,  "  graphic  tellu- 
rium," the  arrangement  of  the  crystals  resembling  Arabic  lettering. 
On  account  of  the  large  percentage  of  gold  in  the  composition  of 
the  richest  ores  of  Cripple  Creek,  it  has  been  concluded  that  the 
prevalent  mineral  is  not  a  silver-bearing  telluride,  but  that  the  gold 
occurs  combined  with  tellurium  alone  in  the  form  of  the  mineral 
calaverite.  Calaverite  is  the  simple  telluride  of  gold,  pure  speci- 
mens contain  44*5  per  cent,  gold  and  55*5  per  cent,  tellurium.  It 
is  named  after  the  county  of  Calaveras,  in  California,  where  it  was 
first  found  at  the  Stanislaus  Mine.  It  usually  carries  from  2  to  3 
per  cent,  of  silver,  which  must  then  be  considered  as  an  impurity. 
The  purest  varieties  have  a  bronze-yellow  colour.  It  is  the  charac- 
teristic mineral  of  the  rich  ores  of  Kalgoorlie,  and  beautiful  speci- 
mens of  it  are  common  in  the  Great  Boulder,  Associated,  and  Lake 
View  Mines  of  that  celebrated  district.  Calaverite  is  rather  difficult 
to  distinguish  from  iron  pyrites ;  the  difference  in  colour  is  slight, 


29 

but  the  former  is  easily  cut  by  a  knife,  while  the  latter  will  not 
permit  of  it.  The  cubic  crystalline  habit  of  pyrites  will  usually 
help  to  make  it  known,  because  calaverite  rarely  occurs  in  any  other 
than  a  massive  form.  The  best  specimens  obtained  in  the  Cripple 
Creek  district  came  from  the  Work  Mine. 

Reference  has  been  made  to  the  uncertainty  as  to  the  identity  of 
the  particular  telluride  mineral  which  carries  the  values  in  many  of 
the  Cripple  Creek  ores.  It  is  very  probable  that  future  investiga- 
tions will  discover  the  existence  of  a  new  variety,  peculiar  to  the 
district,  in  which  many  of  the  physical  characteristics  of  sylvanite 
will  be  united  to  a  composition  so  rich  in  gold  as  to  resemble 
calaverite. 

Petzite,  named  after  the  German  chemist  Petz,  is,  like  sylvanite, 
a  double  telluride  of  gold  and  silver,  its  average  composition  being 
25  per  cent,  gold,  42  per  cent,  silver,  and  33  per  cent,  tellurium. 
It  is  much  darker  than  sylvanite,  being  steel-grey  to  iron-black ;  it 
is  also  slightly  harder  and  more  brittle.  The  best  specimens  of 
petzite  found  in  the  district  came  from  the  Geneva  claim  on  Gold 
Hill,  about  four  years  ago.  Recently  the  writer  found  petzite  in 
the  ore  of  the  Porter  Gold  King  Mine 

All  these  tellurides  are  distinguished  from  the  baser  minerals,  with 
which  they  may  be  occasionally  confounded,  by  their  rich  lustre. 

The  lodes  of  Cripple  Creek  are  further  characterised  by  the 
presence  of  fluorite  or  fluorspar  (the  fluoride  of  calcium),  a  beautiful 
purple  mineral,  which  is  so  notably  associated  with  the  ores  of  the 
district  as  to  have  led  to  the  idea  that  it  could  be  accepted  as  an 
indication  of  the  richness  of  the  veins  in  which  it  was  found.  But, 
like  most  similar  attempts  at  short  cuts  to  knowledge  of  this  kind, 
the  generalisation  has  proved  fallacious.  There  are  several  large 
lodes  of  very  low  grade  ore  in  the  district  which  are  purple  with 
fluorite,  and  there  are  some  very  rich  ores  almost  devoid  of  it. 
The  association  of  the  gold  and  the  fluorspar  points  to  a  similarity, 
and  possibly  a  contemporaneity,  of  origin ;  but  this  fact  does  not, 
and  could  not,  predicate  whether  the  quantity  of  gold  present  will 
give  the  ore  an  average  value  of  $2  or  of  $200  per  ton.  As  a 
matter  of  science,  both  kinds  of  ore  may  be  considered  gold-bearing, 
as  a  matter  of  business,  one  spells  losses  and  the  other  dividends. 

In  the  upper  levels  of  the  mines,  within  the  reach  of  surface 
waters,  the  tellurides  are  decomposed  and  the  gold  has  been 
liberated.  In  the  first  years  of  development,  certain  mines,  such  as 
the  Pike's  Peak  and  Garfield  Grouse,  on  Bull  Hill,  afforded  speci- 
mens of  native  gold,  the  dull  brown  lustreless  appearance  of  which 
was  a  puzzling  variation.  At  Kalgoorlie,  likewise,  a  brittle  spongy 


30 

variety  became  known  as  "  mustard  gold."  In  each  instance,  when 
such  a  specimen  is  scratched  with  a  knife  or  burnished,  the  bright 
gleam  of  pure  gold  is  made  apparent.  These  varieties  of  native 
gold  are  directly  traceable  to  their  origin  from  tellurides,  which 
have  been  decomposed  by  oxidation,  the  gold  often  retaining  the 
form  of  the  original  mineral,  and  being  a  perfect  skeleton  of  u 
former  mode  of  occurrence.  Beautiful  pseudomorphs,  as  they  are 
called,  of  gold  after  sylvanite,*  are  common  in  the  ores  of  Cripple 
Creek. 

Below  the  depth,  which  ranges  from  100  to  400  ft.,  reached  by 
surface  waters,  the  unaltered  tellurides  appear  in  all  their  un- 
tarnished beauty.  At  a  further  depth,  from  500  to  700  ft.,  the  ores 
become  more  complex,  because  of  the  increasing  percentage  of  baser 
minerals,  chiefly  iron  pyrites,  but  including  also  galena  (the  sulphide 
of  lead)  and  stibnite  (the  sulphide  of  antimony).  This  change  is 
important  chiefly  from  a  metallurgical  standpoint,  because  the 
increase  of  "sulphur  renders  the  roasting  of  the  ores  more  expensive. 
The  general  question  of  the  probable  changes  to  be  encountered  as 
the  mines  become  deeper  will  be  discussed  under  another  heading, 
at  the  close  of  this  description  of  the  district. 

THE  TREATMENT  OF  THE  ORES. 

Most  of  the  gold  of  commerce  has  been  won  from  simple  ores, 
those  in  which  the  precious  metal  occurs  in  a  native  condition 
encased  in  quartz.  Stamp-milling,  accompanied  by  amalgamation, 
is  the  process  ordinarily  employed  to  reduce  them.  Another  type, 
of  greater  importance  every  year,  is  represented  by  the  ores  in 
which  the  gold  occurs  intimately  associated  with  iron  pyrites,  but 
so  minutely  disseminated  as  to  be  rarely  visible  even  under  the 
microscope,  and  therefore  inviting  the  supposition  that  it  is  chemic- 
ally combined  in  a  condition  as  yet  not  understood.  A  modified 
form  of  stamp-milling  is  employed  for  some  of  these  ores,  but  for 
the  most  part  they  afford  a  field  for  great  diversity  of  practice, 
including  chemical  and  smelting  processes  of  many  kinds.  The 
third  type  of  gold  mining,  and  in  many  respects  it  is  the  most 
modern,  is  represented  by  ores  in  which  the  gold  is  known  to  be 
chemically  combined  in  definite  proportions  with  the  element 
tellurium.  Several  mining  regions  produce  these  telluride  ores. 
Transylvania  in  Europe,  Colorado  in  the  United  States,  and  West 

*  At  tlie  Gold  Xing  Mine,  in  Poverty  Gulch,  I  recently  secured  specimens 
carrying  crystals  of  gold  pseudomorphic  after  krennerite,  a  mineral  resembling 
calaverite,  but  occurring  in  prismatic  crystals. 


31 

Australia  in  the  Antipodes  are  the  principal  localities.  Transyl- 
vania has  an  interest  which  is  chiefly  historic,  but  Cripple  Creek  in 
Colorado,  and  Kalgoorlie  in  West  Australia,  are  writing  their 
names  in  glittering  figures  on  the  records  of  the  present.  The  new 
phases  of  metallurgical  practice  inaugurated  by  these  recent  dis- 
coveries of  telluride  ores  have  given  a  great  impetus  to  this  technical 
science,  the  aid  of  which  is  now  thoroughly  appreciated  by  the 
miner  and  the  capitalist  alike. 

The  changes  which  have  occurred  since  1891  in  the  treatment  of 
the  ores  produced  by  the  mines  of  Cripple  Creek  are  a  fitting 
illustration  of  the  fact  that  the  development  of  metallurgical  prac- 
tice, like  all  true  progress,  is  a  slow  evolution  from  simple  begin- 
nings to  a  full  fruition.  It  is  a  common  fallacy  to  suppose  that 
processes  of  ore  treatment  are  unexpectedly  discovered  by  rumi- 
nating chemists  or  revealed  from  on  high  to  the  millman,  and  fre- 
quent paragraphs  go  the  round  of  an  ill-informed  press  to  the  effect 
that  this  or  that  spectacled  professor  has  lit  on  a  new  combination 
in  physics  or  chemistry  which  is  to  revolutionise  the  existing 
methods  of  ore  reduction  by  extracting  100  per  cent,  at  a  negligible 
cost.  The  progress  of  metallurgical  practice  resembles  organic 
evolution  in  that  it  does  not  advance  per  saltum.  The  chlorination 
process  was  first  applied,  in  1857,  by  Deetkin,  in  California.  It 
took  a  quarter  of  a  century  of  patient  endeavour  to  place  it  on  a 
safe  commercial  basis.  MacArthur  and  Forrest's  application  of 
potassium  cyanide  was  used,  at  the  Crown  Mine  in  New  Zealand, 
as  early  as  1889,  but  the  chemical  reactions  which  occur  in  the 
cyanide  process  are  still  incompletely  understood  to-day,  and  the 
development  of  this  method  of  ore  treatment  cannot  be  said  to  have 
ceased. 

The  first  ore  broken  at  Cripple  Creek  was  carried  on  the  backs  of 
prospectors  to  Colorado  Springs  or  Florissant,  and  forwarded  to  the 
smelters  of  Pueblo  and  Denver.  Such  small  shipments  of  selected 
ore  usually  mark  the  birth  of  our  western  mining  districts.  Subse- 
quently larger  lots  in  wagons  were  similarly  consigned,  but  the 
costs  were  high  and  the  proportion  of  ore  capable  of  yielding  a 
profit  under  such  conditions  was  small.  The  miner  felt  the  neces- 
sity of  extracting  the  gold  by  milling  it  nearer  the  place  whence  it 
came.  He  fell  back  on  his  previous  experience  in  other  localities 
and  put  up  a  stamp-mill. 

The  stamp-mills  were  built  on  the  model  of  those  of  Gilpin 
County,  the  oldest  gold  mining  district  in  Colorado,  and  therefore 
had  light  stamps,  400  to  500  Ib. ;  a  slow  drop,  30  to  35  per  minute  ; 
a  long  drop,  17  to  20  in. ;  and  a  deep  discharge,  12  to  15  in.  The 


32 


ore  was  broken  by  hammers  and  fed  by  hand  into  the  batteries, 
except  in  the  case  of  the  Rosebud  mill,  which  was  provided  with 
rock-breakers  and  automatic  feeders.  Amalgamation,  on  copper 
plates,  both  inside  and  outside  of  the  mortars,  followed  the  stamp- 
ing. During  the  three  years  succeeding  the  first  discoveries  the 
following  plants  were  at  work  : — 


Name  of  mill. 

Locality. 

Date  of 
erection. 

No.  of 
stamps. 

Lawrence      

1892 

20 

Summit     •••  «« 

Gillett  

1892 

30 

Gold  and  Globe  

Cripple  Creek  

1892 

40 

Beaver  Park             . 

Beaver  Park     

1893 

20 

Colorado  Springs               •  • 

Beaver  Park  

1893 

25 

1893 

20 

Hartzell      .  .          

1893 

20 

Gold  Geiser  

1892 

15 

1893 

20 

Rosebud 

Mound  Citv  •  •                • 

1893 

60 

The  total  is  no  less  than  270  stamps.  In  April,  1897,  only  50 
out  of  this  number  were  dropping,  and  to-day  they  are  all  idle, 
having  been  replaced  by  large  leaching  plants  shortly  to  be  de- 
scribed. 

The  first  ores  came  of  course  from  the  surface,  or  near  it,  and 
were  therefore  oxidised.  The  gold  occurred  in  a  free  state,  having 
been  liberated  from  its  combination  as  a  telluride.  This  last  fact 
was  not  known  and  not  appreciated  even  when  first  it  became 
known.  It  affected  the  milling  most  seriously,  because  gold  having 
this  origin  is  coated  with  a  film  of  the  tellurite  of  iron,  which  is  a 
serious  obstacle  to  amalgamation.  The  extraction  in  the  stamp- 
mills  was  soon  found  to  be  low,  and  attempts  were  made  to  remedy 
the  incompleteness  of  the  treatment  by  employing  bumping  tables 
and  Frue  vanners  to  arrest  the  gold  escaping  amid  the  tailings. 
When  this  failed,  blankets  were  added,  and  these  in  time  became  a 
recognised  addition  to  the  mills.  Even  then  the  best  extraction 
barely  reached  50  per  cent,  of  the  gold  in  the  ore,  as  shown  by 
assays,  and  a  great  deal  of  good  ore  was  wasted  in  an  ineffectual 
effort  to  win  a  profit.  The  usual  rate  for  treatment  was  $3  per  ton, 
delivered  at  the  mill. 

Early  in  the  development  of  the  district  there  came  men  who 
recognized  the  unsuitability  of  stamp  milling  for  the  treatment  of 
telluride  ores,  and  in  1893,  W.  S.  Morse,  of  the  Russell  Lixiviation 
Works,  at  Aspen,  made  the  experiments  which  formed  a  basis  for 


33 


the  erection  of  a  chlorination  plant  built  by  Edward  Holden,  at 
Lawrence,  2  miles  from  the  town  of  Cripple  Creek,  at  the  close 
of  the  same  year,  1893.  Holden  purchased  an  old  stamp-mill  at 
Lawrence  and  altered  it  to  a  chlorination  plant  which,  although  it 
was  crude  and  incomplete,  successfully  demonstrated  the  suitability 
of  the  process  employed.  This  was  barrel  chlorination  on  the 
model  of  the  practice  of  South  Carolina  and  Dakota.  The  erection 
of  the  first  well-designed  plant,  using  this  process,  was  begun  at 
Gillett,  in  August,  1894,  and  completed  in  the  following  January. 
This  had  a  capacity  of  50  tons  per  day. 

The  eyanide  process  had  been  already  tried,  with  results  not 
wholly  satisfactory,  because  of  the  variable  composition  of  the  ores 
and  the  inexperience  of  the  men  who  organised  the  first  milling 
enterprise.  The  local  company,  controlling  the  MacArthur-Forrest 
patents,  built  a  cyanide  mill  of  40  tons  capacity,  at  Brodie,  in  1892. 
It  was*  remodelled  in  1894.  In  1895  the  Metallic  Extraction  Com- 
pany's mill  was  built  near  Florence.  It  has  been  enlarged  from 
time  to  time  and  now  has  a  capacity  of  8,000  tons  per  month.  The 
cyanide  process  made  less  progress  than  barrel  chlorination,  so  that 
while  two  mills  now  employ  this  method,  six  use  the  other.  The 
Colorado-Philadelphia  chlorination  mill  was  built  at  Colorado  city 
in  1896.  It  has  a  capacity  of  6,000  tons  per  month.  The  El  Paso 
mill,  with  a  capacity  of  3,000  per  month  was  built  at  Florence  in 
1897.  The  Gillett  mill  doubled  its  capacity  in  1898.  Others  were 
erected  as  shown  on  the  accompanying  list. 

The  Mills  of  the  Cripple  Creek  District. 


Name. 

Locality. 

Date  of 
erection. 

Capacity 
per  day. 

Ch  farina  Ho  n  — 

Cripple  Creek  

1893 

tons. 
30 

Gillett  

Gillett  

1894 

80 

Colorado-Philadelphia  .  . 

Colorado  City  

1896 

200 

El  Paso   

Florence 

1897 

100 

Colorado  

Arequa                         . 

1897 

75 

Florence    .    .          ... 

1897 

50 

Cyanidation  — 
Brodie   

Cripple  Creek 

1892 

60 

Metallic  Extraction  .... 

1895 

270 

Page  

Florence  .  .                ... 

1896 

20 

The  Lawrence  mill  was  burnt  down  in  1896,  and  the  owners  of 
it  built  the  El  Paso,  at  Florence,   immediately  afterwards.     The 

d 


34 

Page  mill  was  erected  to  use  a  secret  modification  of  the  cyanide 
process,  but  after  a  brief  activity  it  became  idle. 

The  trend  of  events  indicates  that  the  future  growth  of  the 
milling  practice  will  favour  an  increase  in  the  chlorination  mills 
rather  than  in  cyanide  establishments.  At  first,  cyanidation  was 
conducted  upon  raw  ores,  but  this  gave  good  results  only  when  they 
were  oxidised.  Koasting  is  now  considered  a  necessary  preliminary 
and  it  has  removed  the  advantage  which  in  the  earlier  years  of  the 
district  cyanidation  possessed  over  chlorination,  a  process  always 
preceded  by  the  roasting  of  the  material  subjected  to  it. 

The  chlorination  practice  of  the  district  has  undergone  no  radical 
changes  during  recent  years.  It  is  typical  barrel  chlorination.  In 
the  matter  of  the  recovery  of  the  gold  from  solution  there  is  a 
difference,  the  Gillett  mill,  for  instance,  using  charcoal  as  a  pre- 
cipitant, while  the  Colorado-Philadelphia  plant  uses  sulphuretted 
hydrogen.  The  mills  at  Florence  enjoy  an  important  advantage 
in  the  use  of  oil  residuum,  instead  of  coal,  in  their  roasting  furnaces. 
The  residuum  comes  from  the  distillation  of  petroleum  and  costs 
about  1  dollar  per  barrel  now,  although  a  few  years  ago  the  price 
was  much  less.  There  is  an  increased  demand  for  it  because  it 
affords  a  fuel  peculiarly  adapted  for  roasting,  permitting  of  a  nice 
and  quick  adjustment  of  the  temperature  of  the  furnace. 

During  recent  years  the  metallurgical  practice  in  the  chlorination 
plants  has  remained  fairly  constant,  the  improvements  being  in  the 
direction  of  large  capacity  and  better  mechanical  arrangements 
rather  than  in  any  changes  in  the  chemical  department. 

The  cost  of  treatment  at  one  of  the  larger  mills,  having  a 
capacity  of  3,000  tons  per  month,  is,  per  ton  of  ore  treated  :— 

Labour  and  salaries    $1*20 

Chemicals  and  supplies 078 

Fuel     0-65 

Wear  and  tear 0'55 

Incidentals  ..  0*28 


$3-46 

Add  to  this  interest  on  investment,  general  expenses  and  depre- 
ciation of  plant,  and  the  total  costs  will  approximate  $4 '00  per  ton. 
The  above  figures  are  based  on  chloride  of  lime  costing  $2 '40,  and 
sulphuric  acid  $1*25  per  100  Ib.  Koasting  alone  costs  from  45  to 
60  cents  per  ton.  This  item  has  grown  as  the  mines  have  become 
deeper,  the  sulphur  contents  having  increased  from  an  average  of 
1  per  cent,  in  1895  to  2J  per  cent,  at  the  present  time.  The  im- 


35 

provements  in  other  departments   of  the  milling  have  more  than 
balanced  this  change. 

The  ores  are  altered  phonolite,  andesite  breccia  or  granite,  and 
therefore  have  a  composition  similar  to  these  rocks  save  in  an  in- 
creased prcentage  of  quartz.  A  representative  analysis  may  be 
quoted  as 

Alumina 29'94 

Silica    63-13 

Lime    0'70 

Iron  oxide  3*66 

Iron  sulphide 2'64 

Magnesia    trace 

Manganese  oxide    O40 

Sulphur  0-96 

Two  interesting  features  of  Colorado  practice  have  been  brought 
out  by  the  treatment  of  the  Cripple  Creek  ores,  the  first  being  the 
greater  use  of  mechanical  roasters,  such  as  the  Pearce,  Ropp,  and 
other  furnaces,  and,  secondly,  a  modification  of  the  methods  em- 
ployed to  sample  the  ores.  The  material  produced  by  the  mines  is, 
as  compared  with  the  typical  ores  of  other  districts,  high  grade  and 
very  variable  in  its  gold  contents.  This  variability  is  due  to  its 
mode  of  occurrence  as  a  telluride  in  minute  seams  irregularly 
scattered,  and,  of  course,  extremely  rich,  rendering  it  difficult  to 
apply  the  law  of  averages  and  obtain  a  satisfactory  sample  of  a 
large  lot  of  ore.  In  its  passage  from  the  hands  of  the  miner  to 
those  of  the  smelter,  the  ore  usually  goes  through  the  sampling 
works,  the  owner  of  which  may  be  considered  a  broker  whose 
business  it  is  to  see  that  both  parties  in  the  transaction  get  those 
values  in  the  ore  which  one  sells  and  the  other  buys.  It  was  soon 
found  that  Cripple  Creek  ores  were  most  unsatisfactory  to  sample, 
the  results  being  unreliable  and  erratic.  This  became  remedied  in 
process  of  time  by  crushing  a  larger  part  of  any  particular  lot  of 
ore  and  taking  pains  to  pulverize  the  final  pulp  sent  to  the  assay er 
to  100  mesh,*  instead  of  60-  or  80-mesh.  It  has  also  been  found 
that,  on  account  of  the  variability  of  the  ore,  it  is  good  business 
for  the  mine  owner  to  let  all  his  product  pass  through  the  sampler 
on  its  way  to  the  smelter,  and  this  has  led  to  the  erection  of  half  a 
dozen  sampling  works  in  the  Cripple  Creek  district.  The  usual 
cost  of  sampling  is  75  cents  per  ton. 


That  is,  10,000  holes  per  square  inch. 

d  2 


36 


THE  MINES. 


Cripple  Creek  is  interesting  to  the  geologist ;  it  is  fascinating  to 
the  financier.  When  viewed  from  the  latter  standpoint  it  presents 
many  aspects  which  render  it  unique  among  modern  gold  mining  dis- 
tricts. The  mines  of  Cripple  Creek  have  paid  their  own  way  from 
grass  roots,  that  is  to  say,  they  have  not  grown  up  by  the  expendi- 
ture of  working  capital  in  development.  Working  muscle  has  made 
a  10-ft.  hole  into  a  productive  mine.  There  is,  therefore,  an  in- 
stant contrast  between  the  financial  features  of  the  industry  when 
compared  with  the  goldfields  of  the  Transvaal  or  West  Australia. 

It  may  be  objected  that  all  mines  are  first  made  by  the  pick  of 
the  miner  and  are  then  enlarged  into  important  enterprises  by  the 
investment  of  capital  in  machinery  and  development.  Nevertheless 
the  contrast  above  suggested  is  not  a  strained  one,  because  it  is 
a  fact  that  the  mines  of  Kalgoorlie  and  Johannesburg  were  merely 
tracts  of  land  when  they  became  the  basis  for  large  company  flota- 
tions. The  shafts  were  sunk  afterwards  by  the  companies  organised 
in  London,  or  elsewhere,  and  the  ore  was  uncovered  by  workings 
which  had  no  existence  at  the  time  of  the  first  organisation  of  the 
enterprise.  Companies  were  brought  out  with  a  large  subscribed 
capital,  a  portion  of  which  was  paid  out  in  the  purchase  of  property 
and  another  portion  was  set  aside  as  a  working  capital,  that  is, 
a  fund  out  of  which  to  pay  the  expenses  of  equipment  and  that 
amount  of  development  necessary  to  enable  the  mine  to  maintain  a 
steady  production.  It  is  rarely  the  case  that  a  mine  floated  on  the 
London  market  is  able  to  pay  the  increased  dividends  necessitated 
by  an  increased  capitalisation  without  some  preliminary  vigorous 
development  such  as  will  permit  of  an  enlarged  output  without 
exhausting  the  ore  reserves.  In  the  case  of  the  deep-level  mines  of 
the  Eand,  the  working  capital  is  a  princely  sum,  sufficient  to  sink  a 
shaft  a  couple  of  thousand  feet,  or  even  more,  and  erect  a  mill  of 
two  or  three  hundred  stamps.  The  finances  of  South  African 
mining  are  a  study  apart  and  the  result  of  conditions  previously 
unknown  in  gold  mining,  although  paralleled  in  the  coal  industry. 
It  represents  a  wonderful  development  of  modern  practice,  such  as 
renders  the  digging  for  gold  a  steady  business  very  much  unlike  the 
feverish  uncertainties  of  the  days  of  1851  in  California  and 
Australia. 

Even  in  districts  which  have  not  the  extensive  low.grade  deposits 
of  the  Eand,  it  is  necessary  to  provide  for  a  rainy  day,  and  English 
capitalists  are  accustomed  to  the  idea  of  furnishing  a  certain  amount 
of  money  as  a  reserve  fund  to  tide  over  the  lean  places  in  a  mine's 


37 

development.  The  practice  is  a  good  one,  and  to  a  great  extent 
offsets  the  large  capitalisation  of  most  British  incorporations.  The 
American  buys  his  mine  and  proceeds  to  work  it  for  all  it  is  worth, 
the  dividends  are  pocketed,  and  when  the  rich  ore  is  exhausted 
there  comes  a  collapse.  The  shares  of  American  companies  are 
usually  non-assessable;  the  shareholders,  who  receive  the  divi- 
dends, will  often  refuse  to  contribute  fresh  capital,  and  the  mine 
may  be  closed  down  until,  after  an  interval,  some  one  with  a  good 
deal  of  pluck  re-opens  it.  But  this  is  rare.  As  a  consequence 
many  properties  which  made  a  magnificent  record  are  now  idle,  and 
this  idleness  means,  not  inactivity  alone,  but  the  rusting  of  the 
machinery  and  the  falling  in  of  the  workings,  rendering  it  a  very 
costly  matter  to  re-open  the  mine.  The  English  practice  of  heavy 
capitalisation  has  been  censured  often  enough,  but  there  is  this  to 
be  said  for  the  methods  of  London  investors,  that  by  subscribing  an 
adequate  working  capital  they  often  permit  the  mine  manager  to 
enlarge  the  capabilities  of  a  property  so  as  to  enable  it  to  hold  up 
cheerfully  under  its  increased  load  and  continue  exploratory  work 
during  those  intervals  when  the  production  does  not  meet  the 
operating  expenses. 

Our  ways  of  notation  in  Colorado  are  much  more  simple,  and  this 
very  simplicity  would  ruin  any  but  the  best  of  mines.  A  mining 
claim  is  in  the  possession  of  three  or  four  working  miners,  who 
secured  it  originally  by  location.  It  does  not  pay  its  way,  although 
there  is  evidence  that  it  is  worthy  of  development.  They  go  to  a 
couple  of  merchants  in  the  nearest  town,  and  each  of  these  pays  the 
wages  of  one  working  miner  to  represent  him.  The  prospect  hole 
becomes  a  shaft,  and  a  little  good  ore  is  discovered.  A  company  is 
organised  by  a  lawyer  or  a  stockbroker.  The  capitalisation  will  be 
a  million  shares  of  a  nominal  value  of  a  dollar,  but  a  rating  of  10 
or  20  cents  per  share.  The  owners  give  10  per  cent,  of  the  stock  to 
the  incorporator.  Work  is  resumed  with  the  aid  of  the  money 
obtained  by  selling  a  small  block  of  shares.  If  the  mine  does  not 
pay,  it  is  leased  or  some  stock  is  sold.  At  the  best  it  is  a  hand-to- 
mouth  policy,  which  succeeds  in  spite  of  its  weak  points,  because  of 
the  richness  of  the  mine. 

In  other  cases  the  original  working  miner  is  bought  out  for  a  few 
hundred  dollars,  and  the  new  owners  go  ahead  subscribing  the 
money  required  to  meet  expenses,  month  by  month,  until  the 
patience  of  one  or  more  is  exhausted,  and  either  the  impatient 
minority  sells  to  the  plucky  majority  or  the  entire  party  gives  up 
the  fight  for  riches,  and  awaits  a  buyer  who  may  happen  along  at  a 
time  when  the  camp  is  excited  by  new  discoveries  on  neighbouring 
claims. 


38 

The  history  of  Cripple  Creek,  however,  records  comparatively 
few  abandonments,  because  the  veins  have  proved  so  generally  pro- 
ductive that  their  yield  has  sufficed  to  keep  the  work  of  development 
going  ahead,  even  if  it  did  not  meet  all  the  expenses.  As  soon  as  a 
small  mine  becomes  organised  into  a  company,  it  is  listed  on  the 
stock  exchanges  of  Denver  and  Colorado  Springs  as  a  "  prospect," 
and  when  it  becomes  a  regular  producer  it  is  promoted  to  the 
society  of  "  mines,"  the  two  classes  being  kept  distinct  on  the  call- 
lists  of  the  exchanges. 

A  mine  which  does  not  pay  goes  through  eras  of  greater  or  less 
activity,  according  as  the  owners  of  it  can  scrape  together  the 
money  needed  to  continue  the  work.  Idleness  is  possible  because  the 
mining  regulations  do  not  entail  forfeiture  on  that  account.  The 
claim  can  be  "  patented,"  that  is  to  say,  the  owner  obtains  a  title  in 
fee  simple  from  the  U.S.  Government  when  he  has  done  a  certain 
amount  of  work,  nominally  rated  equal  to  the  expenditure  of  |500, 
and  the  Government  surveyor  has  prepared  the  map  needed  for 
record  in  the  bureau  of  the  surveyor-general.  Labour  conditions 
such  as  obtain  in  the  English  colonies  are  unknown  in  Colorado,  and 
the  continuous  operation  of  a  mine  cannot  therefore  be  enforced 
under  the  mining  laws. 

This  is  itself  an  important  feature  of  mining  in  this  State,  and  it 
will  appeal  at  once  to  those  who  have  been  shareholders  of  Aus- 
tralian mining  companies.  I  remember,  when  at  Coolgardie  in 
1897,  what  a  serious  matter  the  labour  conditions  were  to  the  West 
Australian  companies  which  had  acquired  an  extensive  acreage 
during  boom  times,  and  were  compelled  to  work  a  large  force  of 
men  during  a  period  of  financial  stringency.  The  regulations 
required  the  working  of  claims  on  which  no  ore  had  been  found  on 
pain  of  forfeiture,  and,  therefore,  enforced  the  expenditure  of  money 
regardless  of  the  nature  of  the  work  to  be  done.  This  clause  in  the 
mining  law,  which  compels  the  working  of  a  certain  number  of  men 
on  each  claim,  known  in  Australia  as  the  "  labour  covenants,"  has 
its  good  features,  the  chief  being  that  it  prevents  good  mining 
claims  from  remaining  undeveloped  by  those  who,  from  choice  or 
necessity,  would  like  to  pursue  a  dog-in-the-manger  policy.  In  a 
lively  mining  district,  like  Cripple  Creek,  it  is  not  needed,  and 
would  only  impose  irritating  obligations,  but  in  the  older  camps  of 
the  United  States  it  has  led  to  the  severance  from  the  public  domain 
of  large  areas,  which  remain  unexplored  on  account  of  the  poverty 
or  want  of  energy  of  absentee  owners,  who  will  not  exploit  the 
mines,  and  refuse  to  sell  them  save  at  prohibitive  prices.  It  must 
be  remembered  that  an  idle  mine  is  only  a  hole  in  the  ground,  and 


39 

there  is  nothing  more  worthless.  The  problem  is  a  far  reaching 
one,  and  is  only  mentioned  incidentally  because  it  is  still  agitating 
the  mining  departments  of  the  colonial  governments. 

The  leasing  system  is  still  an  important  factor  in  Cripple  Creek 
mining.  Three  or  four  years  ago  it  was  more  prevalent.  The 
owners  of  claims  who  were  too  poor  to  develop  them,  or  too  timid, 
cut  them  up  into  several  sub-divisions  and  leased  them.  The  lessees 
might  be  working  miners,  who  engaged  the  service  of  others  under 
them,  or  the  mine  might  be  leased  to  outside  parties,  who  hired 
workmen  in  the  ordinary  way.  The  period  of  the  leases  varied 
from  six  months  to  two  years,  and  the  royalties  were  15  to  20  per 
cent,  of  the  net  returns,  that  is,  the  receipts  from  the  mill  or 
smelter,  after  the  costs  of  transport  and  treatment  are  deducted. 
Leasing  is  the  last  resort  of  the  perplexed  mine-owner,  and  is  a 
confession  of  inability  to  work  one's  property,  yet  in  the  early  days, 
because  the  mines  were  so  often  owned  by  men  wholly  unfamiliar 
with  mining,  the  system  served  a  good  purpose,  and  many  rich 
mines  owe  their  first  beginnings  to  the  enterprise  of  a  lessee. 

The  history  of  the  mines  is  a  pleasant  one,  encouraging  to  those 
who  have  been  led  by  the  experience  of  other  districts  to  consider 
mining  only  as  a  reckless  gamble  in  which  blind  luck  outweighs 
intelligence.  The  infrequent  transfer  of  mines,  which  has  charac- 
terised the  story  of  Cripple  Creek  up  to  the  present,  is  due  to  the  fact 
that  the  conditions  for  successful  mining  are  present  to  an  unusual 
degree.  In  the  first  place  no  deep  sinking  was  needed  to  reach  the 
ore.  Although  outcrops  were  rare,  and  discovery  was  thus  delayed, 
it  soon  became  evident  that  the  tops  of  the  ore-bearing  veins 
could  be  reached  by  trenching.  The  hills  became  spotted  with 
yellow  heaps  of  rock,  and  it  looked  in  1894  and  1895  as  if  they  had 
been  invaded  by  gophers  of  a  larger  growth.  Ore  was  encountered 
at  depths  of  from  10  to  30  ft.  It  was  rich.  Cripple  Creek  has 
always  been  a  high  grade  camp ;  the  average  yield  for  several  years 
exceeded  3  oz.  per  ton,  and  last  year,  notwithstanding  an  enormous 
increase  in  the  low  grade  milling  ore,  it  was  fully  2  oz.  Therefore, 
even  in  the  earliest  period  of  development,  the  ore  could  meet  the 
costs  of  transport  to  the  smelters.  But  competing  lines  of  railroad 
were  soon  pushed  into  the  district,  and  facilities  for  cheap  mining 
were  obtained  long  before  the  goldfield  had  reached  a  quarter  of  its 
present  importance.  This  fact  permitted  poor  men  to  work  the 
mines,  because  it  gave  them  a  market  for  their  ores ;  muscle  and 
energy  were  sufficient,  capital  was  not  needed  to  the  extent  known 
in  less  favoured  localities.  Even  to  this  day  no  single  mine  has  a 
reduction  plant  of  its  own ;  it  is  not  needed.  As  the  camp  grew, 


40 

the  chlorination  and  cyanide  mills  erected  in  or  near  the  district 
began  to  compete  with  the  smelters,  and  prevented  the  latter  from 
levying  excessive  rates  of  treatment ;  and,  lastly,  the  demoralisation 
of  the  silver  market  already  referred  to  earlier  in  this  description 
as  having  occurred  at  the  time  of  the  closing  of  the  Indian  mints  in 
1893,  which  put  a  severe  check  on  what  was  then  the  chief  industry 
of  Colorado,  did  at  the  same  time  aid  Cripple  Creek  immensely  by 
diverting  the  energies  of  a  very  resourceful  population  to  the 
development  of  the  mines  of  its  newly  discovered  goldfield. 

STATISTICS. 

From  the  first  beginnings  in  1859  to  the  close  of  1898  Colorado 
has  produced — 

Gold 9,512,242  oz.  $196,618,054 

Silver    362,526,541  „  326,482,532 

Lead 1,064,762  tons  87,131,457 

Copper     43,089    „  10,742,167 

The  production  for  1898  is  estimated  to  have  been — 

Proportion  of 
U.8.  output. 

Gold 1,138,584  oz.     $23,534,531  34  per  cent. 

Silver   23,502,601  „         13,690,265  38 

Lead 56,708  tons      4,117,043  26 

Copper 5,435  1,304,504  2 

At  the  present  time  the  mineral  production  of  the  State,  inclu- 
sive of  coal  and  iron,  has  a  value  of  $55,000,000  per  annum. 

There  are  30,000  men  employed  in  the  mines  of  Colorado  out  of 
a  total  population  of  520,000. 

The  smelting  industry  of  Colorado  has  been  an  all-important 
factor  in  the  growth  of  its  mining  districts.  There  are  ten  large 
smelting  works  in  the  State  (at  Denver,  Pueblo,  Leadville,  and 
Durango),  and  several  smaller  plants  whose  activity  is  intermittent. 
The  value  of  the  entire  product  of  the  smelters  amounted  in  1898 
to  $61,000,000.  This  included  the  product  from  ores  which  came 
from  neighbouring  States  and  from  British  Columbia. 

At  the  present  time  3,500  tons  are  smelted  daily  in  Colorado. 
The  annual  tonnage  consists  of  900,000  tons  of  ore,  300,000  tons  of 
iron  flux,  and  185,000  tons  of  limestone,  the  balance  of  the  lime 
needed  being  obtained  in  the  form  of  ores,  which  carry  more  of 
it  than  is  required  for  their  own  treatment.  Aspen  provides  the 
bulk  of  the  latter  material. 


41 

The  charges  for.  treatment  depend  upon  the  composition  of  the 
ore,  particularly  the  ratio  of  iron  to  that  of  silica.  On  a  neutral 
basis  the  charge  is  $4*25  for  oxidised  ores  and  $7  per  ton  for 
sulphide  ores.  On  highly  silicious  ores,  containing  60  to  70  per 
cent,  silica,  the  charge  is  £8  per  ton,  flat.  819  per  oz.  is  paid  for 
the  gold  in  ores  carrying  up  to  2  oz.  per  ton,  and  §19'50  per  oz.  for 
those  which  are  richer. 

Until  1892  silver  mining  was  the  most  important  industry  ;  since 
that  year  gold  mining  has  been  in  the  ascendant.  The  production 
of  gold  has  grown  steadily  and  rapidly,  as  the  following  figures 
testify  : — 

1892    256,410  oz.       $5,539,000 

1893    364,151  ,,  7,527,000 

1894    462,009  „  9,549,730 

1895    656,021  „         13,559,954 

1896    738,618  „         15,267,234 

1897    947,249  „         19,579,637 

1898    1,138,584,,         23,534,53x 

This  increase  is  to  be  credited  chiefly  to  the  development  of 
Cripple  Creek,  the  gain  from  that  district  having  been  the  largest 
part  of  the  improvement  made  by  the  State  in  its  entirety.  The 
output  of  the  Cripple  Creek  district  has  been  : — 

1891  100  oz.  $2,060 

1892  2,821  „  583,010 

1893 104,000  „         2,150,000 

1894  140,710  „  2,908,702 

1895  332,800  „  6,879,137 

1896  363,400  „  7,512,911 

1897  490,500  „  10,139,708 

1898  653,410  „  13,507,349 

The  analysis  of  the  figures  of  the  last  three  years  exhibits  the 
growth  in  the  tonnage  of  ores  treated  by  the  chlorination  and 
cyanide  mills  as  compared  with  the  smelters  : — 

Smelting  ore.  Milling  ore. 

Tons.  Value.  Tons.  Value. 

1896 84,659  £6,045,319  77,388  $1,467,592 

1897 94,287  5,697,788  181,885  4,441,920 

1898 110,036  7,137,366  251,862  6,369,983 

The  smelters  charge  a  minimum  rate  of  $6*50*  on  Cripple  Creek 

*  Smelter  rates  have  gone  up  since  this  was  written,  pending  the  readjust- 
ment of  the  ore  market,  recently  deranged  by  a  labour  strike  which  compelled 
several  of  the  works  to  be  inactive  for  three  months. 


42 


ores,  the  mine  owner  paying  the  cost  of  transport  by  rail,  which 
item  varies  from  $3  to  $5  according  to  the  richness  of  the  ore. 

The  chlorination  and  cyanide  plants  have  the  following  scale  of 
charges  : — 

$7       per  ton  on  ores  carrying  up  to  \  oz.  per  ton. 

7     |O  ,,  ,,  \  55 

8-50  „  „  1 

Q  1  1 

"  11  11  L^  55 

10  „  „  1J 

10-50  „  „  2 

Ores  carrying  more  than  2  oz.  per  ton  are  subject  to  smelter 
rates.  The  mills  pay  $20  per  ounce  for  the  gold.  In  the  above 
charges  is  included  the  cost  of  transport,  varying  from  90  cents  to 
$1*50  per  ton,  which  is  met  by  the  mill  owners.  Thus  on  a  2-oz. 
ore  the  smelter  charge  would  be  $6 -50  plus  the  freight.  $4,  making 
$10-50,  this  being  equal  to  the  milling  rate,  plus  transport,  on  the 
same  ore.  The  consequence  is  that  ores  carrying  less  than  2  oz.  go 
to  the  mills  and  the  richer  stuff  to  the  smelters. 

The  dividends  declared  by  the  mines  ,of  Cripple  Creek  during 
1898  amounted  to  $2,596,144,  but  to  this  figure  must  be  added  the 
profit  made  by  mines  not  owned  by  public  companies  and  also  that 
of  the  numerous  leasing  parties,  bringing  the  total  dividends  to 
fully  $3,000,000. 

Out  of  the  121  American  mines  quoted  as  dividend  payers  on  the 
list  of  the  New  York  Stock  Exchange,  38  are  in  Colorado,  and  23 
are  situated  in  the  Cripple  Creek  district.  A  few  of  the  principal 
ones  among  the  latter  are  quoted  below,  together  with  the  details  of 
their  production. 


Independence  .  .  . 
Portland  

Depth  area.         Production  in  1898. 

-T..   .           Total 

D^vl-.    1  dividends 
dends  in    ,     ~  ,    , 
IQQC     j  to  Oct.  1, 
1899. 

Feet. 

Acres    Tons. 

Value. 

Per 
ton. 

920 

903 
735 
680 
643 
518 
1000 
820 
650 
620 

I 

112        8,378 
183      27,798 
100      13,548 
(150)    31,512 
14        8,252 
30      17,]  83 
11      34,775 
40      22,342 
103      19,329 
n      9,957 

$ 

459,57(5 
1,^79,681 
565.279 
1  ,051,149 
352,329 
536,265 
952,134 
415,863 
576,538 
453,987 

$ 
54-85 
67-62 
41  72 
33-33 
42-67 
31  -21 
30-28 
18-61 
29-83 
45-59 

S        j        S 
220,949    3,062,164 
570,000    2,377,080 
None.    !      472,500 
130,000        240,000 
]  35,000        261,000 
220,000        686,960 
350,000  i  1,555,000 
45,000        228,500 
126,875       253,750 
142,140        256,610 

Isabella    
G-old  Coin  
Moon-  Anchor  .  .  . 
Elkton   
Victor 

Golden  Cycle  .... 
Vindicator 

Lillie  

43 

Some  additional  notes  concerning  a  few  of  the  big  'mines  will  not 
be  out  of  place.  The  Independence  is  one  of  the  pioneer  mines  of  the 
district.  It  was  pegged  out  by  W.  S.  Stratton  on  the  4th  of  July, 
1891,  and  remained  under  his  sole  ownership  until  May  1st,  1899, 
when  he  transferred  it  to  an  English  company,  incorporated  under  the 
name  of  Stratton's  Independence,  Limited.  This  great  mine  has  never 
yet  been  pushed  to  its  full  capacity  for  production.  In  1895  eight  men, 
while  engaged  in  purely  development  work,  broke  ore  which  netted 
an  average  of  $155,000  per  month  for  seven  months  in  succession. 
Of  the  total  area  covered  by  the  property,  not  one  quarter  has  as 
yet  been  explored.  Up  to  May  1st,  1899,  the  mine  had  produced 
44,224  tons,  having  a  gross  value  of  84,071,860  and  yielding  a 
profit  of  82,574,164.  During  the  first  quarter  of  the  new  company 
there  were  produced  9,222  tons,  having  an  average  gold  content  of 
4'02  oz.,  and  a  total  gross  value  of  8708,106.  A  dividend  of 
<£  100,000  was  distributed  on  account  of  operations  from  May  1st  to 
July  31st.  The  ore  reserves  already  opened  up  ensure  a  continuance 
of  this  rate  of  production  for  many  years. 

The  Portland  adjoins  the  Independence  on  the  north.  Of  its 
entire  acreage  only  a  little  over  8  per  cent,  has  been  as  yet  explored. 
During  1898  the  total  receipts  were  $1,890,641,  while  the  expendi- 
ture was  $881,833,  and  the  resulting  profit  $1,008,808.  Dividends 
to  the  amount  of  8570,000  were  distributed,  and  additional  claims 
were  acquired.  The  surplus  carried  forward  was  8668,000.  At  the 
present  time  dividends  at  the  rate  of  24  per  cent,  are  being  paid  on 
the  share  capital  of  83,000,000.  The  total  production  of  this  mine 
to  the  end  of  1898  has  been  109,591  tons,  having  a  value  of 
86,427,523.  The  average  per  ton  is  858-65.  There  have  been 
expended  on  permanent  equipment  8228,213,  and  on  purchase  of 
adjoining  claims  8619,953.  Nevertheless  the  total  dividends  have 
already  been  $2,377,080,  and  there  is  reason  to  believe  that  the  mine 
is  yet  young,  and  destined  to  do  bigger  things. 

The  Isabella  became  famous  early  in  1899  on  account  of  extra- 
ordinarily rich  discoveries  which  permitted  of  a  resumption  of 
quarterly  dividends.  Three  separate  shipments  of  over  50  tons 
each  averaged  45  oz.  of  gold  per  ton.  This  ore  was  obtained  20  ft. 
above  the  ninth  level,  and  the  news  of  it  caused  a  wild  speculation 
in  the  shares  of  the  Company. 

Xext  door  to  the  Isabella  is  the  Victor  Mine,  which  is  said  to 
have  been  bought  in  1893  for  852,000  by  Messrs.  Moffat  and  Smith, 
who  still  control  its  operations.  The  dividends  paid  since  then 
have  an  aggregate  value  22  times  the  purchase  price  of  six  years 
ago.  The  profit  earned  in  1898  was  $323,724.  The  total  output 


44 

to  the  end  of  that  year  has  been  12,242  tons  of  smelting  ore  and 
82,249  tons  of  milling  ore,  having  a  total  value  of  $2,161,186. 

Regarding  other  mines  above  mentioned,  it  remains  but  to  add 
that  most  of  them  have  made  much  larger  profits  than  the  dividends 
indicate,  the  want  of  reserve  capital  causing  the  expenditure  of  part 
of  the  profits  for  the  acquisition  of  adjoining  territory  or  the  carry- 
ing forward  of  a  surplus  to  be  used  as  necessity  arises. 

FUTURE  PROSPECTS. 

In  the  eighth  year  of  its  existence  Cripple  Creek  produced  13 J 
millions,  of  which  22  per  cent,  was  distributed  in  the  form  of 
dividends.  Is  this  to  be  the  height  of  achievement  ?  It  is  less 
difficult  to  foretell  the  career  of  a  young  man  than  the  future  of  a 
mere  child.  Cripple  Creek  has  grown  to  full  manhood,  having 
passed  safely  through  the  ills  of  its  adolescence,  and  has  developed 
a  distinct  character  of  such  stability  that  one  is  justified  in  prophesy- 
ing a  career  of  increasing  success. 

The  present  boundaries  of  the  productive  portion  of  the  district 
are  approximately  identical  with  the  area  occupied  by  the  andesite 
breccia,  and  the  other  rocks  of  the  volcanic  complex.  This  covers 
about  ten  square  miles.  It  is  undoubtedly  the  proper  territory  for 
further  exploration,  and  no  part  of  it  offers  greater  promise  than 
the  line  of  contact  separating  the  breccia  from  the  granite.  Never- 
theless the  geological  conditions  outside  this  circumscribed  area  are 
such  as  to  forbid  hasty  conclusions  discouraging  to  prospecting  in 
the  granite,  which  surrounds  the  district  on  all  sides. 

The  recent  discoveries  of  pay-ore  in  Grassy  Gulch,  and  on  Copper 
Mountain  are  suggestive  of  the  probable  extension  of  the  boundaries 
of  the  goldfield.  It  is  known  that  the  phonolite  dykes  which  are 
associated  with  the  productive  lodes  of  the  central  area  extend  into 
the  outer  granite.  Indeed  several  rich  mines  are  wholly  in  the 
granite,  at  distance  varying  from  a  few  hundred  feet  to  over  2,000 
feet  from  the  breccia.  The  Strong  and  Gold  Coin  are  notable 
examples,  while  among  those  most  distant  from  the  main  mass  of 
the  breccia  may  be  mentioned  the  Orizaba  and  Prince  Albert  on 
Beacon  Mountain,  and  the  Sweet  and  Caledonia,  west  of  Anaconda. 
It  must  not  be  thought  that  these  mines  exhibit  an  ore  occurrence 
wholly  distinct  from  the  main  volcanic  complex ;  such  an  idea 
would  be  unwarranted,  because,  while  they  are  situated  far  outside 
the  mass  of  andesite  breccia,  the  gold-bearing  lodes,  which  they 
develop,  are  associated  with  phonolite,  in  dykes  and  masses.  The 
geology  of  Beacon  Hill  is  especially  characterised  by  a  very  large 
intrusion  of  that  rock. 


45 

It  is  not  extraordinary  that  the  vicinity  of  the  contact  of  the 
granite  with  the  breccia  should  be  a  favourable  environment  for 
large  bodies  of  ore.  The  contact  must  have  been,  at  all  times,  first 
a  line  of  weakness,  next  a  line  of  movement  and  consequent  fractur- 
ing, and  finally  a  line  of  water  circulation.  Thus  there  existed 
the  conditions  which  experience  and  observation  indicate  as  being 
most  favourable  to  mineralisation,  especially  when  to  these  is  added 
the  penetration,  across  the  contact,  of  bodies  of  volcanic  rock, 
such  as  the  dykes  of  andesite,  basalt,  and  phonolite.  Although 
comparatively  little  ore  has  been  found  lying  immediately  upon  the 
contact,  there  is  plenty  of  proof,  in  the  Independence,  Portland, 
and  Granite  Mines,  for  example,  of  the  fact  that  the  lodes  crossing 
it  have  been  beneficiated.  Similarly  the  phonolite  dykes,  when 
they  pass  out  into  the  granite,  have  afforded  a  line  of  weakness 
along  which  fracturing  has  subsequently  occurred,  forming  shattered 
planes  and  lines  of  maximum  porosity  permitting  of  the  circula- 
tion of  the  underground  solutions  which  precipitated  the  precious 
metal.  Every  added  page  of  evidence  only  further  confirms  the 
view,  held  by  the  writer  early  in  the  infancy  of  the  camp,  that 
Cripple  Creek  corroborates  to  a  striking  degree  the  most  modern 
explanations  of  ore  deposition  chiefly  associated  with  the  name  of 
Posepny. 

What  of  the  deep  1  Will  increasing  depth  be  accompanied  by 
impoverishment  1  This  is  not  asked  with  the  timidity  of  a  few 
years  ago  when  the  lodes  had  only  been  followed  two  or  three 
hundred  feet  in  vertical  descent,  and  it  was  foreseen  that  they 
would  eventually  cut  into  the  granite  under  the  breccia.  At  that 
time  the  future  of  the  district  was  uncertain,  and  many  cautious 
men  held  back  in  fear  of  unfavourable  developments.  It  is  obvious 
that  the  mines  near  the  edge  of  the  depression  occupied  by  the 
breccia,  will  penetrate  into  granite  by  sinking  their  shafts  or  by 
extending  their  levels,  as  illustrated  in  the  accompanying  sketch, 
Fig.  7.  This  has  occurred  notably  in  the  case  of  the  Independence 
and  Portland  Mines,  which  reach  the  granite  on  the  southern  and 
western  sides  of  the  territory  owned  by  them.  It  is  very  satis- 
factory to  l)e  able  to  record  the  fact,  that  magnificient  ore-bodies 
have  been  found  in  these  two  properties  upon  veins  which  have 
been  followed  downward  into  the  underlying  granite.  Nor  should 
this  be  surprising  in  view  of  the  discoveries  made  during  recent 
years  in  the  granite  south  and  west  of  the  contact  with  the  breccia. 
If  good  ore  is  found  in  the  granite  at  a  horizontal  distance  of  2,000 
ft.  from  the  mass  of  breccia,  why  should  it  not  be  also  found 
at  a  similar  vertical  distance  below  the  same  formation  1  All  the 


46 

evidence  to  hand  goes  to  show  that  wherever  the  dykes  have 
broken  through  the  rocks  of  the  volcanic  complex,  they  have  per- 
mitted of  ore  deposition,  and  that  therefore  the  possibilities  of 


FIG.  7. 


*      *  ,  «       *  *    -    '  r   <    ox  "#  ''X^  %^ 


gVV)      GRANITE       (V3       BRE 


CCIA 


future  discovery   are  not  limited  to  the  present  restricted  known 
productive  area. 

If  the  mines  of  the  district  were  old,  deep,  worked  out,  one  would 


47 

be  timid  of  foretelling  a  continued  and  advancing  yield  of  gold, 
because  the  brutal  facts  of  experience  do  not  countenance  the  popu- 
lar idea  of  increasing  richness  with  depth ;  but  the  mines  of  Cripple 
Creek  are  young,  comparatively  shallow,  and  only  fractionally 
explored;  each  month's  development,  whether  in  a  lateral  or  a 
vertical  direction,  uncovers  ore  reserves  previously  unsuspected, 
save  by  those  to  whom  painstaking  observation  has  given  a  clue. 

There  is  every  probability  that  the  near  future  will  see  the  intro- 
duction of  capital  from  the  outside,  because  the  production  of  the 
district  has  attracted  the  attention  of  the  larger  financial  centres. 
Nor  is  this  anything  but  desirable.  If  the  sale  of  the  mines  meant 
the  retirement  of  the  present  owners,  their  withdrawal  from  mining 
operations  and  the  transfer  of  the  properties  to  absentee  capitalists, 
the  benefits  of  the  change  might  well  be  questioned ;  but  it  is  a 
fact  that  those  who  control  the  best  mines  also  own  several  smaller 
undeveloped  claims,  and  the  result  of  a  sale  of  any  of  the  big  pro- 
perties would  mean  the  liberating  of  large  sums  of  money  to  be 
used  for  the  opening  up  of  promising  young  mines,  which  now  are 
either  idle  or  incompletely  explored.  The  mining  men  of  Colorado 
have  been  bred  in  the  atmosphere  of  gold-seeking,  and  the  acquire- 
ment of  riches  usually  only  leads  to  larger  operations.  It  is 
unnecessary  to  cite  examples.  They  are  a  part  of  local  history. 

If  the  growing  reputation  of  the  district  should  thus  lead  to  the 
investment  of  large  sums  of  money,  the  immediate  result  would  be 
greatly  to  augment  activity  in  exploratory  work,  and  in  the  wake 
of  this  greater  development  there  will  come,  inevitably,  discoveries 
of  an  importance  eclipsing  those,  the  yield  of  which  is  the  basis  of 
the  present  productiveness. 

The  steady  betterment  in  economic  conditions  tends  continually 
to  decrease  the  working  costs  and  to  make  a  commensurate  addition 
to  the  tonnage  of  ore  available  for  exploitation.  This  is  the  story 
of  all  modern  mining  regions.  The  Rand  illustrates  it ;  Kalgoorlie 
accentuates  it.  There  is  no  immediate  probability  of  any  radical 
change  in  methods  of  ore  reduction  or  transport,  but  there  is  a 
tendency  in  several  directions  to  diminish  the  expense  of  handling 
low  grade  ores.  Two  railroads  tap  the  district,  and  the  competition 
prevents  rates  of  transport  being  unduly  high.  The  building  of  a 
third  line  is  probable,  should  the  production  of  the  camp  increase 
as  it  promises.  Electric  haulage  is  likely  to  become  a  factor  in 
reducing  this  item  of  expenditure.  The  increased  capacity  of  the 
mills,  due  to  their  steady  enlargement  and  the  better  arrangement 
of  the  machinery,  is  permitting  them  to  buy  ores  which  at  one  time 
were  considered  to  have  no  commercial  value.  Thus  five  years  ago 


48 

the  minimum  rate  for  freight  and  treatment  was  $12  per  ton,  while 
to-day  it  is  $7  per  ton.  During  the  same  period  the  smelter  rates 
of  treatment  have  dropped  from  $15  to  $6*50  per  ton.  What  a 
reduction  such  as  this  means,  and  how  great  a  tonnage  of  low  grade 
material  it  transfers  from  the  category  of  rock  to  ore,  will  be 
appreciated  by  those  who  have  watched  the  growth  of  other 
districts. 

The  writer  has  seen  the  development  of  more  than  one  of  the 
great  goldfields  of  the  globe,  and  looking  back  upon  the  brief  history 
of  that  development,  he  recognises  that  those  which  have  pi  oved 
permanent,  share  certain  characteristics  in  common.  In  the  general 
persistence  of  the  ore  bodies,  in  the  size  and  continuity  of  the  lode 
channels,  and  in  the  economic  conditions  favouring  an  easy  realisa- 
tion of  the  values  contained  in  the  ores,  Cripple  Creek  exhibits  the 
features  of  a  great  goldfield,  and  affords  the  promise  of  a  future 
which  will  eclipse  the  achievement  of  the  first  eight  years  of  its 
existence. 


HAEEISOK  AND  SONS,  Printers  in  Ordinary  to  Her  Majesty,  St.  Martin's  Lane. 


SUBJECT  TO   BEVISION-. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Cripple  Creek  Volcano. 

BY  T.    A.    RICKARD,   STATE  GEOLOGIST  OF  COLORADO,    DENVER,   COLO. 

(Washington  Meeting,  February,  1900.) 

THE  Cripple  Creek  district  occupies  a  cluster  of  foot-hills  on 
the  south  side  of  Pike's  Peak  and  is  a  portion  of  an  extensive, 
though  uneven,  plateau  which  unites  the  eastern  range  of  the 
Rocky  mountains  with  the  Sangre  de  Cristo.  It  is  essentially 
a  small  volcanic  area,  of  about  20  square  miles,  amid  the  granite 
of  the  Front  range.  But  though,  when  regarded  as  a  rich 
mining  district,  it  may  be  considered  as  an  isolated  area,*  yet, 
geologically,  it  is,  as  Whitman  Cross  has  pointed  out,  only  an 
outlying  portion  of  a  much  larger  volcanic  region,  whichf 
stretches  to  the  south  and  west,  around  Silver  Cliff  and  the 
Rosita  hills,  forming  the  picturesque  country  cut  by  the  deep 
canons  of  the  Arkansas  river  and  its  tributaries. 

The  mines  are  situated  amid  a  volcanic  complex,  consisting 
of  tuffs  and  breccias  which  have  been  penetrated  by  an  exten- 
sive system  of  dikes  and  other  intrusive  masses.  The  prevail- 
ing formation  is  an  andesite  breccia,  which  lies  upon  the  worn 
surface  of  the  granite  and  fills  the  deep  basin  around  a  volcanic 
vent.  The  breccia,  since  its  deposition,  has  been  broken  into 
by  several  eruptions  of  phonolite  and,  later  still,  by  a  series  of 
thin  dikes  of  basalt  and  other  allied  rocks  of  a  highly  basic 
composition. 

The  successive  sedimentary  formations  which,  elsewhere  in 
Colorado,  lie  upon  the  basal  granite,  are  not  represented  in  the 
district;  whatever  sediments  were  laid  down  before  the  volcanic 
period  must  have  been  removed  by  erosion,  and  there  is  very 
little  evidence  which  affords  a  datum-line  whereby  the  geolog- 
ical age  of  the  volcanic  eruptions  can  be  determined.  Whit- 

*  The  main  mining  belt  of  Colorado  is  30  or  40  miles  to  the  west,  and  extends 
through  Boulder,  Gilpin  and  Summit  counties,  into  Leadville,  and  then  south- 
westward,  through  Aspen,  into  the  San  Juan  region. 

f  " Geology  of  the  Rosita  Hills,  Custer  County,  Colo.,"  by  Whitman  Cross. 
Proceedings  of  the  Colorado  Scientific  Society,  vol.  iii.,  1890. 


2  THE    CRIPPLE    CREEK    VOLCANO. 

man  Cross  has  referred  the  breccia*  of  Cripple  Creek  to  the 
close  of  the  Eocene  period  or  to  the  early  Miocene,  f  This  is 
done  by  correlating  the  small  deposit  of  grit  which  occurs  on 
Straub  mountain,  and  is  the  only  sedimentary  formation  in  the 
district,  with  the  lake-beds  at  Florissant,  15  miles  to  the  north. 
These  celebrated  fossil-beds  belong  to  the  late  Eocene ;  they 
are  largely  made  up  of  volcanic  dust  and  are  covered  by  breccia 
similar  to  that  of  Cripple  Creek.  Moreover,  they  are  overlain 
by  rhyolite  identical  in  character  with  that  which  forms  the 
floor  of  the  gravel-deposit  on  Straub  mountain. 

The  granite  which  forms  the  basal  rock  of  the  region  is 
usually  described  as  Archean.  It  is  probably  Algonkian.  It 
is,  elsewhere,  overlain  by  Upper  Cambrian  strata ;  and  it  has 
been  found  to  include  fragments  of  quartzite  which  are  be- 
lieved to  be  of  pre-Cambrian  or  Algonkian  age.  Therefore 
the  granite  is  not  necessarily  Archean,  but,  to  quote  Dr. 
Cross,  "  older  than  the  only  Cambrian  rocks  as  yet  identified 
in  Colorado."! 

"Within  the  Cripple  Creek  area  the  granite  differs  in  appear- 
ance from  the  rock  which  generally  prevails  in  the  Pike's 
Peak  region.  It  is  a  well  denned  reddish  biotite  (black  mica) 
granite,  and,  instead  of  the  microcline  (feldspar)  which  ordi- 
narily characterizes  the  Pike's  Peak  formation,  it  carries  ortho- 
clase  in  prominent  tabular  crystals.  §  The  quartz  is  usually 

*  The  miners  call  the  breccia  "porphyry."  This  term  is  derived  from  the 
Greek  word  "porphyra,"  meaning  purple.  It  was  first  applied  to  the  beautiful 
dark-red  rock  which  the  Romans  obtained  from  the  quarries  of  Ghebel  Dokhan, 
near  the  shores  of  the  Eed  Sea.  This  original  "porphyry  "  would  now  be  classed 
as  a  porphyrite.  However,  the  original  name,  which  depended  upon  color,  has 
long  since  lost  its  force  in  another  meaning,  which  refers  to  the  structure.  The 
original  "porphyry,"  according  to  Zirkel,  was  speckled  with  snow-white  and 
rose- red  crystals  of  feldspar  in  a  blood- red  ground-  mass.  Hence  the  term  became 
applied  to  rocks  in  which  some  particular  mineral,  frequently  feldspar  or  quartz, 
stands  out  well  defined  from  the  general  matrix,  giving  it  a  spotted  look,  as  for 
example  in  the  familiar  "  bird's-eye  porphyry"  of  the  western  miner.  The  term 
is  often  employed  as  though  it  covered  a  particular  species  of  rock,  while  in  fact 
it  is  merely  a  descriptive  adjective-noun,  covering  any  kind  of  crystalline  rock 
having  a  mottled  appearance  due  to  the  predominant  development  of  one  of  its 
constituent  minerals  in  individual  crystals. 

f  "  Geology  and  Mining  Industries  of  the  Cripple  Creek  District,  Colorado," 
by  Whitman  Cross  and  R.  A.  F.  Penrose,  Jr.,  IMA  Ann.  Rep.  U.  S.  Geol.  Sur., 
Part  II,  p.  18,  1895.  The  writer  owes  a  great  deal  of  his  descriptive  geology  to 
this  valuable  monograph.  £  Op.  tit.,  p.  17. 

%  I  obtained  some  fine  twin  crystals  (Carlsbad  type),  2£  inches  long,  from  the 
top  of  Bull  Hill. 


THE    CRIPPLE    CREEK    VOLCANO.  3 

iron-stained,  and  the  mica  shows  the  commencement  of  a 
change  into  green  chlorite.  The  oligoclase,  which  occurs  as  a 
subordinate  feldspar,  shows  a  ready  tendency  to  decomposition, 
especially  near  the  ore-bodies  in  the  mines. 

Turning  to  the  examination  of  the  breccia,*  we  find  that  it 
consists  of  a  consolidated  mass  of  fragmentary  material  having 
a  coarseness  comparable  to  gravel.  Occasionally  the  pieces 
are  as  large  as  a  man's  hand ;  but  these  are  rare.  More  fre- 
quently the  breccia  is  very  fine,  and  then  comes  under  the 
designation  of  "  tuff."  It  is  mainly  composed  of  augite-andesite, 
in  which  smoky-brown  prismatic  crystals  of  apatite  occur. 
The  feldspar  is  kaolinized,  and  the  dark  silicates,  such  as  augite 
or  biotite,  have  undergone  destruction  by  leaching.  While  the 
mass  of  this  formation  is  made  up  of  andesite,  it  exhibits, 
locally,  a  good  deal  of  fragmental  phonolite  and  granite,  the 
latter  more  particularly  in  the  vicinity  of  the  contact.  Fine 
pyrite  is  distinguishable  in  most  specimens.  In  the  upper 
workings  of  the  mines  the  kaolinization  of  the  feldspar  has 
given  the  rock  a  bleached  appearance ;  and  at  the  surface  the 
iron  oxides,  derived  from  the  alterations  of  the  pyrite,  have 
stained  it  yellow  or  red.  Fluorite  is  a  frequent  constituent, 
wherever  the  breccia  is  penetrated  by  the  gold-bearing  veins, 
and  colors  it  a  dark  purple.  The  finer  tuffs  are  often  so  silicified 
as  to  be  undistinguishable,  except  under  the  microscope,  from 
massive  rocks.  The  decomposed  breccia  also  exhibits  the 
healing  effects  due  to  the  infiltration  of  secondary  quartz  ;  and, 
when  it  is  included  within  the  boundaries  of  any  of  the  ore- 
deposits,  the  soluble  ingredients  have  been  removed  to  such  an 
extent  as  to  leave  often  only  a  pumice-like  remnant  of  inter- 
lacing quartz. 

Penetrating  the  mass  of  the  breccia  and  extending  into  the 
surrounding  granite,  there  is  an  intricate  series  of  dikes,  chiefly 
of  phonolite. f  This  is  usually  a  light-colored  rock  of  even 

*  "Breccia"  and  "tuff"  are  both  words  of  Italian  origin.  We  owe  many 
terms  describing  volcanic  materials  to  the  study  of  Vesuvius.  "  Breccia  "  means 
"broken."  It  is  applied  to  rocks  made  up  of  a  consolidation  of  angular  frag- 
ments. "Tuff"  is  employed  both  for  a  rock  built  up  of  fragmental  material  of 
smaller  size  than  that  composing  a  "breccia,"  and  also  for  the  rock  resulting  from 
the  mud  caused  by  the  action  of  water  upon  volcanic  dust.  In  the  latter  sense, 
the  original  Italian  word  "  tufa  "  is  made  use  of  by  many  authorities. 

f  "Phonolite  "  is  derived  from  the  Greek  words  "  phone,"  sound,  and  "lithos," 
stone.  The  close  texture  and  even  grain  of  the  phonolite  causes  it  to  give  a  ring- 


4  THE    CRIPPLE   CREEK   VOLCANO. 

texture  and  sherd-like  fracture ;  but  the  conditions  of  its  occur- 
rence, in  thin  and  in  thick  dikes,  in  almost  horizontal  sheets, 
and  in  shapeless  intrusive  cores,  are  so  varied  as  to  have  in- 
duced a  great  many  modifications  in  its  physical  characteristics. 
The  essential  constituents  are  sanidine  (the  glassy  variety  of 
orthoclase)  and  nepheline.  The  crystals  of  the  latter  are  occa- 
sionally sufficiently  developed  to  give  the  rock  a  porphyritic 
appearance.  Besides  the  normal  phonolite  there  are  allied 
rocks,  such  as  trachytic*  phonolite  and  nepheline-syenite,f  oc- 
curring under  various  structural  conditions.  There  are  also 
dikes  of  andesite,J  similar  in  character  to  the  earlier  rock 
which,  in  its  fragmental  form,  composes  the  bulk  of  the  breccia. 
Finally,  crossing  these  rocks,  and  therefore  last  in  the  sequence 
of  eruption,  are  the  dikes  of  nepheline-basalt  with  which  im- 
portant ore-bodies  are  associated  on  Eaven  hill  and  Battle 
mountain. 

The  Cripple  Creek  district  represents  the  ground-floor  of  a 
volcano,  §  the  superstructure  of  which  has  been  removed  by 
erosion.  Let  us  consider  what  this  means.  Among  the  gains 
of  modern  science  there  is  none  more  striking  than  the  elucida- 
tion of  the  causes  which  bring  about  the  terrifying  phenomena 
of  volcanic  action.  A  hundred  years  ago,  an  active  volcano 
excited  superstitious  fear,  and  was  regarded  only  as  a  catas- 
trophic interruption  to  the  order  of  nature.  Since  then,  the 
patient  researches  of  sucK  men  as  Spallanzani,  Scrope  and  Judd 
have  enabled  us  to  recognize  in  these  activities  the  orderly 
operations  of  forces  subject  to  definite  laws. 

ing  sound  when  struck  with  a  hammer.     In  England  it  is  often  called  "clink- 


stone. 

*  "  Trachyte  "  is  from  the  Greek  word  meaning  "  rough."  The  rock  usually 
has  an  uneven  fracture,  due  to  the  angular  sanidine  and  the  porosity  of  the  ground- 
mass. 

t  "Syenite"  comes  from  the  Greek  Syene,  the  town  in  Egypt  now  known  as 
Assouan.  It  is  a  curious  fact  that  it  has,  comparatively  recently,  been  found  that 
the  rock  at  Assouan  is  not  a  typical  syenite,  which  is  a  variety  of  granite  contain- 
ing very  little  quartz,  with  hornblende  replacing  the  mica.  It  is  really  a  red 
granite,  very  much  resembling  that  of  Pike's  Peak.  The  Egyptians  quarried  it 
for  their  obelisks,  and  out  of  it  they  built  the  Temple  of  the  Sphinx  at  Ghiseh. 

J  "Andesite"  is  derived  from  Andes,  the  mountain  range  in  South  America 
where  it  is  particularly  prevalent. 

$  The  word  "volcano  "  is  Italian.  It  was  the  name  given  to  one  of  the  Lipari 
Islands  in  the  Mediterranean,  where  quiet  eruptive  action  has  been  going  on  since 
the  tinie  of  the  ancients,  who  considered  the  little  mountain-island  as  the  forge  of 
the  Roman  god  Vulcan. 


THE    CRIPPLE    CREEK    VOLCANO.  5 

The  scope  of  scientific  investigation  has  included  not  only  the 
observation  of  existing*  volcanic  action,  but  also  the  examination 
of  the  remains  of  extinct  volcanoes.  The  structure  of  the  latter 
has  thrown  light  on  the  behavior  of  the  former.  As  the  story 
of  the  development  of  forms  of  life  now  extinct,  but  preserved 
in  fossil-beds  and  recorded  for  us  by  the  palaeontologist,  ad- 
vanced our  insight  into  the  structure  of  living  things,  while 
biology  repaid  the  aid  thus  received  from  palaeontology  by  con- 
tributing the  clues  through  which  the  incomplete  evidence  of 
the  rocks  was  so  correlated  as  to  demonstrate  the  sequence  of 
strata,  so  the  study  of  the  volcanoes  of  to-day  led  geologists  to 
recognize  the  results  of  similar  action  in  masses  of  rock,  the 
eruptive  origin  of  which  was  previously  unsuspected,  and,  in 
turn,  the  deciphering  of  the  skeletons  of  extinct  volcanoes  ad- 
vanced the  understanding  of  those  which  have  survived.  Nat- 
ural sections  gave  the  requisite  testimony.  Atmospheric  ero- 
sion, acting  through  vast  periods  of  time,  has  cut  into  the 
mass  of  many  of  the  ancient  volcanoes  of  the  earth  so  as  to  un- 
cover their  anatomy.  The  dissection,  by  Professor  Judd,  of 
the  old  volcano  of  Mull,f  in  the  Western  Isles  of  Scotland,  is 
an  excellent  example  of  this  method  of  research.  Occasionally 
mine-workings,  or  excavations  made  for  other  purposes,  afford 
valuable  evidence  as  to  the  internal  structure  of  volcanic  moun- 
tains. The  Eammerbuhl,  in  Bohemia,  is  a  curious  instance.  J 
It  is  a  small  hill,  apparently  of  no  particular  interest,  but, 
nevertheless,  it  was  once  the  subject  of  a  hot  scientific  discus- 
sion. The  poet  Goethe  took  part  in  the  dispute,  and  persuaded 
a  friend,  Count  Sternberg,  to  drive  a  tunnel  into  the  hill  with  a 
view  to  settling  the  question  of  its  origin.  The  result  justified 
Goethe's  claim  that  it  was  "  a  pocket  edition  of  a  volcano.'' 
It  was  found  that  the  hill  consisted  of  a  mass  of  volcanic  scoria, § 
through  the  center  of  which  passed  a  plug  of  basalt.  The  plug 
obviously  occupied  the  choked-up  vent  of  the  volcano,  from 
which  proceeded  a  lava-stream  which  had  flowed  over  the  flank 
of  the  hill.  Fig  1  illustrates  this  statement. 

*  There  are  about  350  active  volcanic  vents  on  the  surface  of  the  earth  at  the 
present  time. 

f  Quarterly  Journal  of  the  Geological  Society,  vol.  rxx. ,  p.  220,  etc. 

t  See  Judd's  "Volcanoes,"  pp.  112-114. 

\  "Scoria  "  is  a  Latin  word,  unchanged.  It  is  used  especially  for  coarsely  ve- 
sicular lava,  but  often  for  fragmental  lava  in  general. 


THE    CRIPPLE   CREEK   VOLCANO. 


n.  •< 
O"' 


THE    CRIPPLE    CREEK    VOLCANO.  7 

At  Cripple  Creek,  the  mine-workings  afford  a  good  deal  of 
information  concerning  the  underground  structure  of  the  region. 
It  is  hoped  that  an  inquiry  into  the  history  of  the  volcano 
which  determined  the  interesting  character  of  the  district  will 
contribute  towards  a  clearer  comprehension  of  the  geology  of 
the  mines. 

The  operations  of  nature  in  the  past  are  inferred  from  the 
observation  of  those  which  take  place  to-day.  The  intensity  may 
vary;  the  forces  are  the  same.  This  is  the  corner-stone  of 
modern  geology  as  laid  down  by  Lyell.  The  volcanic  complex 
at  Cripple  Creek  is  to  be  understood  in  the  light  of  the  evidence 
gathered  for  us  by  the  patient  investigators  who  have  stood  by 
the  side  of  the  craters  of  Stromboli,  Vesuvius  and  Kilauea. 

The  conclusions  of  those  who  have  made  a  specialty  of  this 
branch  of  geology*  may  be  summarized  thus :  The  explosive 
violence  of  volcanic  eruptions  is  due  to  the  access  of  water  to 
the  fused  rock  within  the  conduit  of  the  volcano ;  but,  as  it  ap- 
pears that  this  water  is  not  contained  within  the  substancef 
of  the  lavaj  emitted  during  the  tranquil  emissions  succeeding 
the  first  paroxysmal  outburst,  it  is  inferred  that  the  water  is  not 
the  primary  cause  of  volcanic  action,  which  originates  at  a  depth 
greater  than  that  to  which  it  is  believed  that  water  can  pene- 
trate. The  evidence  collected  is  not  complete ;  but  it  warrants 
a  reasonable  conjecture  that  volcanoes  owe  their  origin  to  the 
contraction,  caused  by  the  cooling,§  of  the  earth's  crust  upon  a 
yielding  substratum,  separating  the  solid  outermost  shell  from 
an  equally  solid  nucleus.  ||  While,  therefore,  the  force  which 

*  Among  the  best  literature  on  the  subject  may  be  mentioned  Volcanos  by 
Poulett-Scrope,  Volcanoes  by  Judd,  and  Characteristics  of  Volcanoes  by  Dana. 

f  That  is,  "  occluded." 

J  Lava  is  Italian  for  "stream."  It  is  from  the  same  Latin  root  as  lave,  lava- 
tory, etc.  Although  the  term  is  usually  applied  to  the  fused  material  emitted  by 
a  volcano,  it  is  often  employed  in  referring  to  the  same  rock  after  it  has  become 
consolidated,  especially  when  the  rock  has  not  been  specifically  classified. 

\  ' '  Secular  refrigeration .' ' 

||  The  question  of  the  condition  of  the  earth's  interior  is  too  large  for  extended 
reference.  Besides  the  standard  text-books  on  geology,  the  reader  will  find  much 
suggestive  matter  in  Osmond  Fisher's  "Physics  of  the  Earth's  Crust,"  and  in 
Prestwich's  "  Controverted  Questions  of  Geology."  There  is  also  a  summary  of 
the  evidence  regarding  this  subject  in  the  address  of  Sir  William  Thompson 
(Lord  Kelvin)  before  the  meeting  of  the  British  Association  in  1876.  The  gen- 
eral conclusions  of  science  have  been  lately  expressed,  in  a  popular  way,  by  Pro- 


8  THE    CRIPPLE    CREEK   VOLCANO. 

pushes  large  quantities  of  fused  rock  to  the  exterior  of  the  earth 
has,  probably,  a  deep-seated  origin,  nevertheless,  the  imme- 
diate cause  of  the  uncertainty,  the  violence  and  the  magnificent 
energy  of  volcanic  action  is  traceable  to  the  effects  produced  by 
water  coming  into  contact  with  the  lava  as  it  approaches  the 
surface. 

The  destructive  energy  of  a  volcano  may  be  likened  to  a 
boiler-explosion ;  volcanoes  may  be  considered  the  safety-valves 
of  creation.  The  mass  of  incandescent  rock  which  is  slowly 
being  squeezed  upward  meets  a  large  volume  of  water  which 
flashes  into  steam  with  a  sudden  expansion  causing  the  most 
astounding  results.  One  cubic  foot  of  water  yields  1700  cubic 
feet  of  steam.  It  is  accepted  by  specialists  that,  whatever  the 
ultimate  origin  of  volcanic  action  may  be,  the- surface  effects 
are  due  to  the  explosive  escape  of  accumulations  of  steam  sud- 
denly released  from  pressure.  This  explanation  is  based  upon 
accurate  observation  of  the  quiet  workings  of  the  miniature 
volcanoes  of  the  Lipari  Islands,  in  the  Mediterranean,  and 
upon  the  evidence  obtained  during  the  more  violent,  apparently 
paroxysmal,  outbursts  of  Vesuvius,  Etna,  Tarawera,  Kilauea 
and  Krakatoa. 

The  volcanic  rocks  of  the  •  Cripple  Creek  district  have  come 
up  through  the  granite.  It  underlies  them  all ;  they  rest  upon 
it,  and  can  be  seen  penetrating  it  in  the  form  of  dikes.  Pre- 
vious to  the  first  eruption,  the  granite  must  have  presented 
a  weather-worn  surface,  such  as  characterizes  the  high  hills. 
Ever  since  its  first  emergence  from  the  ocean  this  region  has 
been  undergoing  an  intermittent  elevatory  movement,  which 
culminated  in  making  the  Front  range.  Erosion  had  been  con- 
tinuous, but  the  uplift  more  than  counterbalanced  such  wear- 
ing away  ;  and  the  granite  hills  had  been  slowly  raised  far  above 
the  Cretaceous  seas  which  washed  their  edges  in  the  era  pre- 
ceding that  to  which  the  eruption  is  assigned.  The  forces 
which  had  done  this  work  were  of  the  most  patient  kind  ;  their 

fessor  Milne,  thus:  "The  earth  became  solid  under  two  influences;  it  began  to 
solidify  at  the  surface  by  cooling,  the  crust  growing  thicker  and  thicker  ;  and  it 
began  to  solidify  at  the  center  by  pressure,  the  core  growing  larger  and  larger. 
This  double  phenomenon  of  solidifying  continued  until  a  solid  outer  shell  and  a 
solid  inner  core  came  close  together  in  what  may  be  called  the  critical  region  of 
the  earth,  the  region  which  feeds  lava  to  volcanoes." 


THE   CRIPPLE    CREEK   VOLCANO.  9 

manifestation  had  about  it  nothing  of  a  violent  or  paroxysmal 
character;  time  was  an  essential  element  of  the  process. 

At  the  close  of  the  Eocene  period  this  apparent  equilibrium 
was  disturbed.  The  foundations  of  the  granite  hills  trembled. 
Slight  tremors  were  followed  by  earthquakes,  and  these  were 
the  precursors  of  greater  violence. 

Earthquakes  usually  precede  an  eruption.  In  certain  vol- 
canic regions,  such  as  the  north  island  of  New  Zealand  and 
Japan,  the  minor  shocks,  designated  as  "  tremors,"  are  of  daily 
occurrence.  They  represent  the  vibrations  set  up  by  the  sud- 
den generation  of  steam  from  water  coming  into  contact  with 
the  upwelling  lava.  It  is  water-vapor,  and  not  smoke,  which 
is  emitted  by  volcanoes.*  This  water  is  derived  from  the  sur- 
face, having  sunk  into  the  soil,  permeating  the  more  porous 
sedimentary  rocks,  lodging  in  the  crevices  of  unstratified  for- 
mations, and  becoming  stored  underground,  as  mine-explora- 
tions testify.  Where  the  country  surrounding  the  volcanic 
vent  has  become  covered  with  the  products  of  previous  erup- 
tions, the  loose  character  of  the  soil,  resulting  from  the  dis- 
integration of  scoriaceous  lava,  facilitates  the  descent  of  the 
rains,  and  tends  to  the  accumulation  of  large  quantities  of 
water.  Moreover,  the  vibrations  set  up  by  the  superheated 
steam  cause  fissures  which  allow  distant  bodies  of  water,  from 
subterranean  reservoirs,  fresh-water  lakes,f  or,  if  the  volcano 
be  situated  near  the  coast,  the  ocean  itself,  to  be  let  downj  sud- 
denly into  the  volcanic  vent  and  into  explosive  contact  with  the 
incandescent  lava.  Humboldt§  found  small  fishes  in  the  water 

*  Volcanoes  are  not  necessarily  mountains.  The  mountain  is  the  result  of  the 
volcano,  and  not  vice  versa.  It  is  the  accumulation  of  the  material  ejected  from 
the  vent  which  slowly  builds  up  the  cone.  Many  emissions  of  lava  occur  at  the 
base  of  mountain  ranges  and  have  quietly  overspread  the  surface  from  fissures, 
much  as  water  rises  through  cracks  in  the  ice  and  overspreads  it,  when  a  heavy 
wagon  presses  it  down.  The  lava-plains  of  the  Snake  river,  traversing  Oregon 
and  Idaho,  afford  an  example;  so  does  the  Deccan  (India),  where  successive, 
nearly  horizontal,  flows,  covering  an  area  of  200,000  square  miles,  have  reached 
a  thickness  of  6000  feet. 

f  Lake  Rotomahana  was  drained  at  the  time  of  the  eruption  of  Tarawera,  in 
New  Zealand,  in  1886. 

J  Mosely  (Notes  by  a  Naturalist  on  the  Challenger,  p.  503)  mentions  that,  in 
1877,  when  on  board  the  "Challenger,"  he  saw  the  sea- water  actually  pouring 
down  into  a  fissure  formed  in  the  bed  of  the  sea  off  the  Hawaiian  coast.  The  fis- 
sure was  traced  to  the  shore  and  three  miles  inland.  This  occurrence  was  con- 
nected with  the  volcanic  activity  of  Mauna  Loa,  on  the  neighboring  island  of 
Hawaii.  |  Controverted  Questions  of  Geology,  Prestwich,  p.  116. 


10  THE    CRIPPLE    CREEK    VOLCANO. 

emitted  from  fissures  caused  by  earthquakes  in  the  Andes. 
Diatoms,  the  microscopic  forms  of  life  characterizing  the  deep 
sea,  have  been  found  in  the  volcanic  ejections  of  the  Pacific 
islands.  Where  volcanoes  are  in  proximity  to  the  ocean  it  has 
been  found  that  among  the  emanations  from  the  lava  there 
exist,  not  only  chlorides,  but  also  sea-salt  itself.  A  sudden 
diminution  of  the  water-supply  in  wells  and  springs  near 
Naples  has  been  repeatedly  observed  to  presage  the  eruption  of 
Vesuvius. 

There  is  therefore  ample  evidence  that  water  does  penetrate 
into  the  conduit  of  the  volcano,  and  that  it  is  originally  derived 
from  the  surface.  As  against  the  contrary  belief,  namely,  that 
the  water-vapor  accompanying  eruptions  is  an  essential  con- 
stituent of  the  lava,  and  therefore  shares  with  it  a  deep-seated 
origin,  there  is  the  following  evidence.  It  has  been  found,  as 
the  result  of  a  large  number  of  accurate  observations  in  wells, 
shafts  and  bore-holes,  that  the  temperature  underground  in- 
creases 1°  F.  for  every  48  feet  of  descent.*  At  7776  feet,  the 
boiling-point,  and  at  34,700  feet,  the  critical  point,  773°  F.,  of 
water,  would  be  reached.  The  expansive  force  of  steam  in- 
creases rapidly  with  the  temperature,  so  that  at  773°  F.  it  would 
be  equal  to  the  pressure  of  350  atmospheres. f  This  is  termed 
the  "critical  point,"  because,  at  this  temperature,  water,  how- 
ever great  the  pressure  to  which  it  is  subjected,  can  no  longer 
exist  as  a  liquid,  but  becomes  dissociated  into  its  constituent 
gases.  Although  the  exact  conditions  which  obtain  at  these 
great  depths  cannot  be  known  with  certainty,  nevertheless, 
all  the  evidence  goes  to  show  that  there  is  a  limit  set  to  the 
descent  of  surface-water  by  the  rapid  increase  in  the  expansive 
force  of  its  vapor,  due  to  the  rising  temperature.  PrestwichJ 
put  the  maxim  limit  at  6  to  7  miles,  and  Delesse§  estimated  it 

*  ''On  Underground  Temperatures,"  Sir  Joseph  Prestwich.  Proceedings  of  the 
Royal  Society,  February,  1885.  Of  course  this  increment  of  1  degree  per  48  feet 
can  only  apply  to  the  outermost  portion  of  the  earth.  Beyond  a  few  miles  of 
depth  there  must  exist  conditions  of  which  very  little  can  be  inferred.  There, 
the  enormous  pressure  probably  counteracts  the  expansive  effects  of  heightened 
temperature,  and  upsets  many  of  the  conclusions  of  physics  which  hold  good  near 
the  surface. 

t  Which,  at  15  Ibs.  per  square  inch  for  each  atmosphere,  amounts  to  about  2J 
tons  per  square  inch. 

J    Controverted  Questions  of  Geology,  p.  93. 

g  Bulletin  Societe  Geol.  de  France,  vol.  xix.,  p.  64. 


THE    CRIPPLE    CREEK    VOLCANO.  11 

at  60,000  feet,  or  about  11  miles.  Moreover,  experience  goes 
to  show  that  the  water  encountered  in  mines  is  the  drainage 
from  the  surface.  Deep  mines  are  usually  dry  ones.  I  may  in- 
stance the  deepest  metal-mines,  the  Calumet-Hecla  and  Tama- 
rack, in  the  Lake  Superior  region,  and  the  "180,"  "New  Chum- 
Victoria,"  and  neighboring  shafts,  at  Bendigo,  in  Australia. 

The  evidence  obtainable  concerning  the  first  eruption  of  the 
Cripple  Creek  volcano  is  necessarily  very  meager.  The  first 
vent  must  have  been  formed  at  some  point  along  one  of  the 
fractures  caused  by  the  earthquake-shocks;  the  lava, in  forcing 
for  itself  a  way  to  the  surface,  being  aided  by  the  force  of  the 
expanding  steam.  The  pressure  required  to  break  a  passage 
through  the  overlying  rocks  is  stupendous ;  and,  as  a  conse- 
quence, when  the  steam  accompanying  the  lava  is  finally,  and 
very  suddenly,  released  from  that  pressure,  on  its  immediate 
arrival  at  the  surface,  it  escapes  with  explosive  energy,  and  with 
projectile  discharges  which  may  reach  to  an  astonishing  height. 
Thus,  when  the  outburst  of  Krakatoa,  an  island  near  Java,  oc- 
curred in  1883,  the  finer  fragments  ascended  skyward  10  miles, 
and  were  recognizable*  in  the  atmosphere  of  London.  The 
winds  carried  the  dust  of  Krakatoa  round  the  world,  and  thus 
gave  rise  to  the  extraordinary  sunsets  observed  in  the  autumn 
following. 

The  material  ejected  during  the  first  outburst  of  a  volcano 
consists  of  fragments  of  rock  torn  from  the  sides  of  the  vent- 
The  extinct  volcano  of  the  Kammerbuhl,  already  mentioned  in 
this  paper,f  exhibits  pieces  of  burnt  slate  within  the  mass  of 
the  scoria  forming  its  cone.  The  underlying  formation  consists 
of  slates  and  other  metamorphic  rocks. 

The  Cripple  Creek  volcano  first  ejected  fragments  of  granite. 
These  were  probably  small  in  size,  and  became  further  re- 
duced by  colliding  with  each  other  as  they  were  discharged, 
so  that  they  fell  to  earth  in  showers  of  particles  like  gravel.  Of 
this  first  eruption  there  is  little  trace  now,  unless  the  grits  of 
Straub  and  Grouse  mountains  be  the  remnants,  as  is  probable,  J 

*  The  writer,  then  a  student  at  the  Koyal  School  of  Mines,  saw  this  volcanic 
ash  under  the  microscope  after  it  had  been  collected  from  the  London  atmosphere, 
which  hardly  needed  solid  contributions  from  such  a  distant  source. 

f  See  Fig.  1  and  the  corresponding  text. 

J  This  is  the  opinion  of  Whitman  Cross.     See  page  71,  op.  cit. 


12  THE    CRIPPLE    CREEK    VOLCANO. 

of  the  debris  accumulated  at  that  time.  Material  resembling 
this  must  certainly  have  covered  the  surface  around  the  vent, 
until  the  larger  portion  of  it  was  washed  away.  The  steam 
which,  in  enormous  volumes,  accompanies  the  first  outbursts 
of  volcanic  action,  becomes  condensed  as  soon  as  it  issues  into 
the  cold  air  and  forms  rain-clouds,  the  downpouring  of  which 
frequently  removes  the  accumulations  formed  at  the  inital  stage 
of  the  volcano.  The  floods  which  succeed  eruptions  are  due  to 
the  super-saturation  of  the  atmosphere  with  the  water-vapor 
emitted  by  the  volcano.  Such  floods  are  more  feared  by  the 
dwellers  around  Vesuvius,  for  example,  than  the  lava-streams, 
the  destructive  effects  of  which  are  comparatively  restricted.  It 
was  the  formation  of  a  liquid  mud,  by  the  action  of  heavy  rains 
on  the  fine  material,  called  "  tufa,"  which  buried  the  city  of 
Herculaneum. 

It  is  unlikely  that  sufficient  data  will  ever  be  forthcoming  to 
give  an  exact  presentation  of  the  chief  vent  of  the  Cripple 
Creek  volcano,  unless  one  of  the  millionaires,  enriched  by  the 
gold  he  has  won  from  the  mines,  shall  prove  as  public-spirited  as 
Goethe's  friend,  and  shall  undertake  the  requisite  explorations. 
Yet  some  very  interesting  evidence  on  this  point  is  available. 
A  miniature  vent*  exists  near  the  town  of  Victor,  and  the 
railroad  has  cut  through  it,  so  as  to  furnish  the  section  of  it 
shown  in  Fig.  2.  As  a  hand-specimen  may  exemplify  the 
structure  of  a  mountain  range,  so  this  small  vent  typifies  many 
of  the  characteristics  of  the  orifice  probably  existing  in  the 
earlier  stages  of  the  Cripple  Creek  volcano. 

This  vent  occurs  in  the  massive  granite  of  Squaw  mountain, 
about  1700  feet  south  of  the  main  breccia-formation  of  Battle 
mountain.  In  the  railroad-cut,  where  it  is  to  be  seen,  it  has  a 
width  of  35  feet.  It  is  filled  with  fragments  of  granite  and  the 
gravel  derived  from  the  brecciation  of  granite.  The  edges  are 
not  particularly  well-defined,  because  the  face  of  the  enclosing 
rock  is  shattered.  The  most  peculiar  feature  of  the  section  is 
presented  by  pellets,  nodules  and  rounded  fragments  of  dark- 
red  scoriaceous  lava,  which  occur  all  through  the  material  filling 
the  vent.  At  the  edges,  rounded  inclusionsf  of  this  lava  can  be 

*  Whitman  Cross  describes  this  vent  on  page  77  of  his  Cripple  Creek  report. 

f  The  largest  are  1  to  1£  inches  in  size.  On  microscopic  examination  Professor 
Kemp  found  it  difficult  to  determine  the  exact  petrographic  character  of  this  lava. 
"It  shows  only  alteration  products  in  some  parallel  arrangement,  but  not  in  sig- 


THE    CRIPPLE    CREEK   VOLCANO. 


13 


seen  in  the  mass  of  fragmentary  granite ;  and  in  the  center  the 
lava,  by  reason  of  oxidation,  forms  a  red  granular  matrix,  in 
which  large  pieces  of  granite  are  separately  discernible.  The 


£-^- — r^-^V-w.  iv   ^v  A   - 

" 

:^^^^Si^S^^^^^$;^M 


material,  especially  near  the  edges,  has  a  laminated  structure, 
parallel  to  the  sides  of  the  vent.  These  laminations  vary  in 
thickness  according  to  the  coarseness  of  the  material. 

nificant  condition."  In  both  of  the  specimens  I  sent  to  him  he  detected  large 
scales  of  biotite.  Having  in  view  this  fact,  and  the  character  of  the  material,  it 
seems  most  probable  that  the  lava  closely  resembles  the  rock  of  the  basaltic  dike 
in  which  the  neighboring  Anna  Lee  ore-chimney  was  found  to  occur. 


14  THE    CRIPPLE    CREEK    VOLCANO. 

This  illustration  is  of  great  interest.  The  vent  is  in  granite, 
as  was  the  first  vent  of  the  volcano.  It  is  now  filled  with  breccia, 
as,  at  one  time,  that  was.  The  shattering  of  the  sides  is  sug- 
gestive of  the  mode  of  formation  of  the  breccia,  which  now  fills 
it.  Had  this  vent  been  further  enlarged,  and  subsequently  pene- 
trated by  phonolite,  not  in  fragments,  forming  a  breccia,  but  in 
liquid  form,  solidifying  to  a  compact  mass,  it  would  have  pre- 
sented a  complete  analogy  to  the  Cripple  Creek  volcano. 

As  another  example,  but  from  a  different  locality,  of  a 
natural  section  of  a  small  vent,  I  would  instance  that  shown  in 
Fig.  3,  which  represents  a  drawing  recently  made  by  Sir  Archi- 
bald Geikie,*  while  traveling  among  the  Faroe  Islands,  in  the 
North  Atlantic  ocean.  The  action  of  the  waves  has  cut  down 
the  face  of  the  cliff,  so  as  to  exhibit  its  structure  very  clearly. 
The  vent  occurs  in  banded  lava  (A  A)  and  has  a  diameter  of 
about  100  yards.  It  is  filled  with  agglomerate  (B)  consisting 
of  compacted  debris,  in  which  lie  large  fragments  of  slaggy 
lava,  the  largest  being  in  the  center  of  the  former  orifice.  The 
filling  is  arranged  in  distinct  layers  toward  the  sides.  The  top 
of  the  vent  is  saucer-shaped,  and  is  covered  with  three  succes- 
sive fiows  of  basalt  (D,  G,  E) ;  of  these,  the  lowest  has  merely 
extended  over  the  center  of  the  vent,  while  the  next  (D)  nearly 
covers  it,  and  the  uppermost  (G)  lies  over  the  whole  of  it. 
Above  these  there  are  other  layers  of  basalt  (E,  F)  which  com- 
pletely bury  the  orifice. 

After  the  first  outburst,  a  change  took  place  in  the  matter 
ejected  by  the  Cripple  Creek  volcano;  there  began  to  appear 
the  fragmentary  andesite  which  was  destined  to  be  accumulated 
to  such  an  enormous  thickness.  It  may  be  that  flows  of  ande- 
sitic  lava  also  welled  out  over  the  surface  at  this  time.  If  so, 
they  were  subsequently  eroded.  During  the  long  intervals  of 
quiet  separating  one  period  of  eruption  from  another,  the  lava 
became  cooled,  cracked,  arid  then  disintegrated  by  rain  and 
frost,  so  as  to  be  broken  up  and  -carried  away  by  the  moun- 
tain streams  to  form  a  part  of  the  alluvium  of  the  valleys. 
Thus  the  superficial  flows  were  removed ;  but  the  corresponding 
bodies  of  lava  which  consolidated  underground,  when  the  ex- 
trusion at  the  surface  had  ceased,  are  now,  thanks  to  that  very 

*  "The  Tertiary  Basalt  Plateaux  of  North  Western  Europe."  Quarterly 
Journal,  Geological  Society,  vol.  lii.,  page  344. 


THE    CRIPPLE    CREEK    VOLCANO. 


15 


erosion,  to  be  seen  as  bodies  of  andesite  rock  in  several  parts  of 
the  district,  notably  on  the  eastern  side  of  Battle  mountain  and 
near  Legal  Tender  Hill,  above  Goldfield.* 

The  fragmentary  eruption  of  andesite   continued.     At  this 
time  the  volcano  must  have  been  a  splendid  sight,  especially  by 


night.  It  was  so  late  in  geological  time  that  Pike's  Peak  was 
already  a  giant  among  its  fellows,  and  towered  in  lonely 
grandeur  above  the  lesser  hills  where  the  eruption  was  taking 

*  As  the  accompanying  geological  map  (Fig.  4 )  of  the  district  illustrates.  This 
map  is  a  reduced  copy  of  the  colored  map  published  by  the  United  States  Geo- 
logical Survey.  The  ideal  section  which  I  have  drawn  (Fig.  5)  is  taken  in  an 
east  and  west  line  across  the  southern  part  of  the  area. 


16 


THE   CRIPPLE   CREEK   VOLCANO. 


FJC,*: 

f   4-       4- 


4-      +       •*        -V        4     .  4-       •»•       -f      4 
1-4-*         4        4       -f-       <-       ...       4. 

J_  »  •  _!__£_  _L  i 


+       4 
* 


4      -       -        4-       +          t    jjA! 

4-44^  _4-x ^^rl1 

f        *       t        +X/T'xv^    + 

4-        4        +jf+*rt^'¥ 

4         +        +    ^tA        -        -H 


.  .^^a  +^  -+x   T-  iv    "t*  ii 

aii^^Mi 

^+"  «BRG^riMBI^  +*/.*%**  **  *t***»*f 

+X+^H&1"*  |piBPr''¥-%  %  *V  r  *-  %  **%% 

4-         4-     -«-^^^»4.         t^B^^^^/4-        4-        4        ^H-1-4-  t-44-i- 

,  Scale ,  l  mile 

Trachytic  Phonolfte  [_£p  Andesite  flB  Nepheline-Syenite  /  Basalfr 

^JP  Phonolite  $'<:'£j  Andesite  Breccia  ["+  .  fl  Granite^ 


Nepheline-Syenite 
^"}  Granite^ 
^^5  Arkoee  Gravels 


|  Rhyolite 


GEOLOGICAL  MAP  OF  THE  CRIPPLE  CREEK  DISTRICT. 
(After  U,S.  Geological  Survey.) 


rDiabase 


,.  . 

place.     The  shifting  lights  of  the  volcano  were  reflected  by  the 
snow-fields  of  the  peak.     Those  lights  were  due  to  the  glow  of 

* 


snow 
the 


-es  o   te  pea.          ose    gts  were    ue  to  te  gow  o 
incandescent  lava  in  the  crater  thrown  upon  the  clouds*  of 

*  Professor  Judd  very  aptly  likens  this  effect  to  that  caused  when,  at  night, 
the  engineer  of  a  locomotive  pulls  ppen  his  furnace  door  and  permits  the  light  of 
the  fire  to  be  thrown  upon  the  stream  of  vapor  issuing  from  the  funnel. 


THE    CRIPPLE    CREEK    VOLCANO. 


17 


watery  vapor  which  hovered  overhead.     To  this  appearance* 
were  added  lightning-flashes.     The  steam  issuing  through  the 


Hir 

^r,-m$$m  / 

•'^t'^&m^ 

10     S1    U    r  i^V^K'^"'''"''^^ 

2  Wi^SS^  n 

141  W^iftbalfe^l 


x  i:^/s»5 
.  ;v,\rv 

»'  >N.-;:^; 

$m 


§       oc 
>      o 

1 1 


orifice  of  a  volcano  is  highly  charged  with  electricity,  generated 
by  its  upward  rush,  and  the  friction  of  the  colliding  particles 

*  The  old  idea  of  a  volcano  was  a  mountain  which  spouted  fire,  ashes  and 
smoke.  The  "fire"  is  the  reflection  referred  to  above  ;  the  "smoke"  is  vapor  ; 
the  "ashes  "  are  lava  rendered  vesicular  or  pumice-like  by  the  bubbles  of  steam 
penetrating  fused  rock. 

2 


18  THE    CRIPPLE    CREEK    VOLCANO. 

of  solid  matter  ejected  with  the  steam  contributes  further  in 
producing  a  condition  of  intense  electrical  excitement.  This 
is  relieved  by  discharges  into  the  surrounding  atmosphere. 

The  lightning  illuminated  the  surrounding  hills  and  shone 
around  Pike's  Peak;  the  hurtling  of  the  fragments  of  rock  as 
they  met  in  mid-air  and  the  sound  of  their  fall  as  they  rattled 
down  the  slope  of  the  volcano  mingled  with  the  muffled  roar 
of  escaping  steam  and  the  occasional  rumbling  of  the  thunder. 

There  was  none  to  see  it.  Man  was  not  yet  on  earth,  though 
the  footsteps  of  his  oncoming  could  almost  be  heard.*  Of 
animal  life  no  traces  have  been  found  in  the  Cripple  Creek 
formation.  Bird  and  beast  fled  from  the  terrible  sights  and 
sounds.  But  remnants  of  the  vegetation  of  that  time  have 
been  preserved,  and  at  depths  of  many  hundred  feet  beneath 
the  surface  of  to-day  the  miner  has  encountered  the  remainsf 
of  trees,  resembling  pines,  which  were  overwhelmed  by  the 
eruption. 

At  this  period  similar  outbursts  .were  occurring  among  the 
neighboring  hills,  for  the  Cripple  Creek  volcano  was  but  a 
minor  incident  among  the  eruptions  which,  during  the  Tertiary 
epoch,  spread  a  vast  thickness  of  breccia  and  lava  over  a  large 
portion  of  southern  Colorado.  Out  of  the  products  of  these 
eruptions  were  sculptured  the  serrated  peaks  of  the  Uncom- 
paghre,  the  Cochetopa  hills,  and  the  rugged  ranges  of  the  San 
Juan. 

After  the  eruption  had  continued  sufficiently  long  to  form  a 
vast  accumulation  of  the  fragmentary  materials,  which  in  pro- 
cess of  time  became  consolidated  into  breccia,  there  came  a 
period  of  comparative  quiet. 

*  The  earliest  vestiges  of  man  belong  to  the  close  of  the  Miocene  period. 

t  These  are  various.  In  the  Jack  Pot  mine,  at  400  feet  from  the  surface,  in  the 
Logan  at  600  feet,  and  in  the  Doctor  at  700  feet,  there  have  been  found  fragments 
of  coal,  exhibiting  traces  of  wood -structure  In  the  Independence,  at  5CO  feet,  a 
stump  of  a  tree  was  discovered  in  the  very  midst  of  rich  ore  In  every  case  the 
enclosing  rock  was  breccia.  The  specimen  from  the  Independence  is  stone,  the 
others  are  coal.  In  the  former  case,  the  tree-portion  must  have  become  buried 
under  conditions  free  from  access  of  air,  and  must  have  been  subjected  sub- 
sequently to  the  action  of  siliceous  waters,  which  gradually  replaced  the  fiber  of 
the  wood  with  a  mineral  precipitate.  In  the  other  cases,  the  tree  must  have  be- 
come enclosed  within  the  breccia  and  subjected  to  a  slow  oxidizing  action  which 
carbonized  the  wood,  without  permitting  it  to  burn  freely.  Otherwise,  it  would 
have  been  destroyed,  leaving  only  ashes  As  it  was,  it  became  coal,  carrying  60 
per  cent,  carbon,  and  having  the  other  characteristics  of  a  typical  lignite. 


THE    CRIPPLE    CREEK    YOLCANO.  19 

The  Cripple  Creek  volcano  must  have  formed  a  conspicuous 
mountain.  This  is  inferred  from  the  nature  of  the  material 
ejected.  The  size  and  shape  of  the  cones  formed  by  the  emis- 
sions of  a  volcano  depend  upon  the  condition  in  which  they 
are  emitted.  Limpid  lavas,  like  those  of  the  Hawaiian  vol- 
canoes, form  extremely  flat  cones.  Mauna  Loa,  for  example, 
has  a  height  of  13,675  feet  above  the  sea,  with  a  base  of  over 
70  miles,  the  slopes  having,  according  to  Dana,  an  angle  of 
4°  to  6°  only.  The  great  volcanic  cones  of  the  Andes  are 
made  up  of  a  much  less  liquid  lava,  and,  according  to  Whym- 
per,  have  slopes  which  range  from  27°  to  37°.  Mount  Shasta, 
in  California,  which  is  built  up  of  similar  rocks,  stands,  accord- 
ing to  Whitney,  at  an  angle  ranging  from  28°  to  32°.  A  cone 
such  as  that  formed  around  the  vent  of  the  Cripple  Creek  vol- 
cano, which  emitted  vast  quantities  of  fragmental  material 
alternating  with  occasional  lava-flows  of  the  more  viscid  type, 
would  partake  of  the  character  of  the  well-known  puys  or  peaks 
of  Auvergne,  which  dot  the  surface  of  that  part  of  south-central 
France,  in  shapes  resembling  a  candle-extinguisher.  Breccia 
and  lava  together  make  steeper  cones  than  lava  or  breccia 
separately ;  therefore  the  Cripple  Creek  volcano,  when  at  its 
maximum  height,  must  have  appeared  as  a  steep  mountain. 

Projectile  discharges  were  succeeded  by  tranquil  emissions 
of  lava.  The  bodies  of  massive  andesite  in  the  southeastern 
part  of  the  district  may  represent  such  extrusions.  They  were- 
marked  by  an  absence  of  the  violence  which  accompanied  the 
earlier  outbursts,  due,  perhaps,  to  a  diminution  in  the  quan- 
tity of  escaping  steam  and  a  lessening  of  the  pressure  upon  that 
which  remained.  The  earlier  ejectamenta  of  a  volcano  are 
scoriaceous  and  vesicular ;  that  is,  they  have  been  penetrated  and 
torn  by  the  explosive  escape  of  superheated  water-vapor,  while 
the  lava  characterizing  the  later  stages  of  activity  is  compact 
and  homogeneous.  The  creation  of  a  vent  serves  as  a  safety- 
valve  in  releasing  the  tremendous  pressure  of  the  steam,  due  to 
its  sudden  expansion  when  coming  into  contact  with  incandes- 
cent fused  rock.  Attendant  upon  the  relief  given  to  that  pres- 
sure, are  all  the  terrifying  phenomena  of  the  first  outburst.  Sub- 
sequently the  force  of  the  eruption  diminishes.  The  lava  ceases 
to  be  violently  projected  by  escaping  high-pressure  steam.  The 
underground  waters  near  the  conduit  have  become  used  up. 


20,: 


»'     •>  s     J> 

I*  i  *,j 

THIS    CRIPPLE    CREEK    VOLCANO. 


The  rise  of  the  lava  underground,  followed  by  its  protrusion  at 
the  surface,  becomes  a  quiet  process,  which  must  be  referred  to 
a  more  deep-seated  cause,  namely,  the  local  readjustment  of 
the  earth's  crust,  causing  the  fused  rock  to  ooze  out  slowly. 
Many  lava  streams  have  a  glacier-like  movement.  They  seldom 
progress  more  than  3  miles  per  day,  and  often  require  a  year 
to  advance  a  few  miles.*  Observers  have  described  the  flows 
of  lava  which  follow  the  first  eruption  as  welling  out  "  with  the 
tranquility  of  a  water-spring,"f  as  "  proceeding  in  silence,"J 
as  "  being  effected  quietly  and  without  noise. "§  All  this  is  in 
vivid  contrast  to  the  paroxysmal  outburst  which  marks  the  first 
stage  of  volcanic  activity.  The  difference  is  to  be  referred  to 
the  relative  quantity  of  steam  taking  part  in  the  process  of 
eruption. 

The  period  of  quiet  may  have  been,  and  probably  was,  suc- 
ceeded by  a  complete,  though  temporary,  cessation  of  activity. 
This  interval  may  have  persisted  for  several  hundred  years. 
Geology  is  lavish  of  time.  The  inaction  was  due  to  the  diminu- 
tion of  pressure  consequent  on.  the  withdrawal  of  the  lava  in 
the  conduit  of  the  volcano.  Such  a  result  would  be  brought 
about  by  the  shifting  of  the  center  of  eruption  to  another  place 
along  the  line  of  fissure.  The  island  of  Yulcano,  in  the  Lipari 
group,  affords  an  excellent  example  of  such  a  change  of  vent. 
Among  the  extinct  craters  of  Auvergne||  in  south-central 
France,  similar  instances  are  numerous.  (See  Fig.  6.)  The 
first  conduit  of  the  Cripple  Creek  volcano  became  plugged  up 
by  material  which  had  failed  of  ejection.  Other  minor  vents 
may  have  been  formed  on  the  flanks  of  the  mountain  which 
had  been  slowly  formed  by  the  long  continuance  of  discharges. 
When,  after  an  interval,  a  vigorously  active  condition  was  re- 
sumed, the  second  eruption,  in  all  probability,  took  place 
through  a  new  vent,  produced,  as  the  original  one  had  been, 
by  a  fissuring  of  the  rock  immediately  over  congested  masses 
of  steam  due  to  the  water  which  had  accumulated  during  the 
interval  of  inaction. 

*  Dana.  f  Scrope.  J  Fouque.  \  Ibid. 

||  The  writer  cannot  claim  to  have  any  special  knowledge  of  volcanoes,  but  he 
is  familiar  with  the  volcanic  region  of  Auvergne,  in  south-central  France,  has 
seen  Vesuvius,  and  has  traveled  in  the  volcanic  parts  of  New  Zealand,  and  also 
in  Oahu,  one  of  the  Hawaiian  Islands. 


THE    CRIPPLE    CREEK   VOLCANO. 


21 


There  is  evidence  indicating  that  the  Cripple  Creek  volcano 
had  several  vents.  One  existed  near  the  present  site  of  the 
Hull  City  placer ;  another  must  have  been  situated  near  Ana- 
conda. The  original  position  of  the  orifice  of  an  extinct  vol- 
cano can  be  inferred  from  the  composition  of  the  rocks.  The 
lava  which  cools  rapidly  in  the  open  air  assumes  the  character 
of  a  glassy  substance,*  containing  only  a  few  embryonic 


FIG.  6. 


SECTION 
THE  PUY  DE  PARIOU,  AUVERGNE. 

ILLUSTRATWG  THE  SHIFTING  OF  ERUPTION  ALONG  A  LINE  OF  FISSURES. 
(AflfeaJudd.) 


crystals,  but  that  which  cools  slowly  underground,  and  while 
still  subjected  to  great  pressure,  is  developed  into  completely 
crystalline  rock.  Experiments  with  smelter-slags,  and  a  micro- 
scopic examination  of  the  resulting  material,  have  confirmed 
this  proposition.  In  this  way  the  lava  streams  which  have 
issued  from  the  vent  are  distinguishable  from  the  material 

*  On  June  3,  1840,  a  stream  of  lava  from  Kilauea  reached  the  sea,  after  having 
flowed  over  the  island  of  Hawaii  for  a  distance  of  11  miles.  "  The  burning  lava, 
on  meeting  the  waters,  was  shivered  like  melted  glass  into  millions  of  particles, 
which  were  thrown  up  in  clouds  that  darkened  the  sky  and  fell  like  a  storm  of 
hail  over  the  surrounding  country." — DANA,  Characteristics  of  Volcanoes,  page  63. 


22  THE    CRIPPLE    CREEK    VOLCANO. 

which  has  solidified  in  the  throat  of  the  volcano.  The  nephe- 
line-syenite near  the  Lillie  and  Vindicator  mines  is  the  granular 
equivalent  of  the  phonolite  which  occurs  so  plentifully  all  over 
the  district.  The  phonolite  and  the  syenite  have  a  similar 
chemical  composition,  but  their  texture  is  very  different.  This 
is  due  to  the  fact  that  in  the  former  a  crystalline  structure  has 
not  been  fully  developed,  but  the  ground-mass  or  matrix,  as 
seen  under  the  microscope,  being  made  up  of  crystallites, 
minute,  hair-like  bodies  without  the  properties,  but  with  the 
tendency  to  become,  crystals.  This  indicates  that  the  rock 
cooled  too  rapidly  to  permit  of  proper  crystalline  growth.  The 
nepheline-syenite,  on  the  contrary,  is  made  up  entirely  of  de- 
veloped minerals,  no  part  of  the  original  ground-mass  having 
failed  of  arrival  at  true  crystalline  maturity;  so  that  even  the 
slight  excess  of  quartz,  though  uncombined,  presents  a  crystal- 
line structure.  This  indicates  that  the  rock  cooled  very  slowly, 
giving  ample  time  for  the  full  play  of  the  forces  which  pro- 
duce crystallization.  It  is  to  be  inferred  that  the  nepheline- 
syenite  fills  an  old  vent,  or  is  close  to  it.  The  same  inference 
is  drawn  from  the  patch  of  syenite-porphyry  between  Gold  hill 
and  Squaw  gulch.  Further  evidence  suggestive  of  the  former 
existence  of  a  vent  thereabouts  is  afforded  by  the  steepness 
of  the  plane  of  contact  between  the  granite  and  breccia  on 
the  adjoining  Guyot  hill.  The  dissection  of  extinct  volcanoes 
in  other  parts  of  the  world,  a  dissection  brought  about  by 
natural  erosion,  which  has  cut  valleys  right  into  the  flanks  of 
ancient  eruptive  centers,  furnishes  numerous  examples  con- 
firming such  deductions  as  have  just  been  made  with  reference 
to  the  vents  of  the  Cripple  Creek  volcano.  Even  in  Great 
Britain,  which  has  not  known  volcanic  disturbances  during  the 
time  covered  by  the  brief  record  of  human  life,  there  are  abun- 
dant proofs  concerning  the  shifting  of  vents  and  the  resulting 
relations  between  perfected  and  undeveloped  rock-types. 

The  occurrence  of  several  vents  would  not  be  unusual.  Vol- 
canoes are  not  mere  bores  through  which  eruptive  discharges 
take  place.  Where  one  single  vent  survives,  it  may  be  con- 
sidered to  represent  the  centralization  of  energy  due  to  the 
choking-up  of  many  other  openings  along  the  line  of  fissure 
formed  at  the  time  of  the  first  manifestation  of  activity.  This 
is  well  illustrated  in  the  accompanying  sketch  of  Mount  Etna, 


THE    CRIPPLE    CREEK    VOLCANO. 


23 


as  it  appeared  in  1865.  (See  Fig.  7.)  The  expansive  force  of 
the  steam,  to  which  the  violence  of  the  initial  stages  of  vol- 
canic action  is  due,  tends  to  radiate  from  the  central  point  of 
energy  so  as  to  form  cracks,  the  character  and  extent  of  which 
will  vary  according  to  the  structure  of  the  rocks  through  which 
the  shocks  are  propagated.  At  certain  points  along  these 
cracks,  or  at  the  crossing  of  two  of  them,  openings  are  formed, 
permitting  eruptive  discharge.  Those  openings  which  are  im- 
mediately above  the  points  of  greatest  pressure,  will  survive 
longest;  the  others  become  plugged  up  with  the  material  they 
are  unable  to  eject.  One  vent  usually  remains  as  the  center  of 


Monte  Frumento,  an  old  Parasitic  Cone  B  B       Line  of  Fissure  C  C  C       New  Scoria  Cones 

D  D      Lava,  from  the  small  Scoria  Cones 

FISSURE  FORMED  ON  THE  FLANKS  OF  MT.  ETNA  IN  1865. 

(After  Judd.) 

energy.  The  others  become  extinct,  until  an  increase  of  erup- 
tive activity  finds  a  single  conduit  insufficient,  and  thus  neces- 
sitates the  obtaining  of  relief  at  other  points.  Lava-flows  do 
not  necessarily  take  place  at  the  central  .vent.  Many  of  the 
largest  flows  known  to  have  occurred  among  the  Hawaiian 
volcanoes,  for  example,  have  emanated,  not  from  the  crater  at 
the  top  of  the  mountain,  but  far  down  upon  its  flank.  In  cer- 
tain instances,  as  at  Kilauea,*  the  larger  number  of  discharges 
have  been  subterranean. 

The  subterranean  discharges  of  lava  are  of  peculiar  interest 

*  Dana.    That  of  July,  1840,  started  at  a  point  16  miles  distant  from  the  crater. 


24 


THE    CRIPPLE    CREEK   VOLCANO. 


to  the  miner,  because  they  are  among  the  factors  which  he  has 
found  by  experience  to  influence  the  distribution  of  the  ores 
which  he  seeks.  They  are  to  be  seen  both  in  natural  sections, 
afforded  by  ravines,  and  in  those  other  sections  of  the  rocks 
which  are  presented  underground  in  the  mines.  ,  The  accom- 
panying drawing,*  after  Fouque  (see  Fig.  8),  of  a  natural  sec- 
tion seen  on  the  slope  of  the  old  volcano  of  Santorin,  will  be 
suggestive.  These  intrusions  take  a  variety  of  forms.  Such 
as  seek  out  the  lines  of  weakness  presented  by  the  bedding- 
planes  of  sedimentary  rocks,  or  the  lines  of  successive  deposi- 


FiG.8, 


Lava  flows 


Dykes 


f     Scoria  and  Ash 


SECTION  ON  THE  SLOPES  OF  THE  OLD  VOLCANO  OF  SANTORIN 
(After  Fouque) 

tion  of  fragmentary  volcanics,  form  sheets.  In  England,  such 
an  intrusive  sheet  is  termed  a  "sill."  An  instance  is  illustrated 
in  the  accompanying  section,  obtained  in  the  western  islands  of 
Scotland  by  Sir  Archibald  Geikie.f  (See  Fig.  9.)  The  intru- 
sive masses  of  porphyry  (quartz-felsite)  which,  at  Leadville, 
penetrate  the  sedimentaries,  afford  an  example  which  is  of 
peculiar  interest  on  account  of  the  remarkable  ore-deposits 
found  at  the  contact  of  the  porphyry  with  the  Carboniferous 
limestone. 

*  From  Santorin  et  ses  Eruptions. 

f  "  The  Tertiary  Basalt-Plateaux  of  Northwestern  Europe." — Quarterly  Journal 
Geol.  Soc.,  vol.  lii.,  p.  377. 


THE    CRIPPLE    CREEK    VOLCANO. 


25 


Those  subterranean  flows  of  lava  which  do  not  find  a  ready 
passage,  either  in  a  lateral  or  a  vertical  direction,  tend,  when 
thus  impeded,  to  congest  locally,  so  as  to  form  huge  under- 


CQ 


ground  blisters  which  are  sometimes  large  enough  to  arch  the 
overlying  strata  into  dome-shaped  hills.  Such  "  laccolites,"* 
as  they  are  termed,  were  first  recognized  as  a  type  by  G.  K. 

*  From  the  Greek  lakkos,  cistern,  and  lithos,  stone.     Laccolith  would  be  a  better 
form. 


26 


THE    CRIPPLE    CREEK    VOLCANO. 


Gilbert.*  Since  then,  Whitman  Crossf  has  described  similar 
occurrences  in  southwestern  Colorado.  The  accompanying 
drawing  (Fig.  10)  represents  his  ideal  section  of  one  of  these 
enormous  cores  of  what  was  once  fused  rock.  In  this  particular 
section,  of  Mount  Marcellina,  it  is  evident  that  the  porphyrite 
has  arched  the  overlying  coal-bearing  strata  to  the  point  of  rup- 
ture, a  line  of  fracture  being  indicated  to  the  right  of  the 
laccolite. 

Such  intrusive  masses  as  have  been  described  are  encoun- 
tered by  the  miner  with  much  less  frequency  than  the  dikes, 
which  are  approximately  vertical  sheets  of  igneous  rock,  evi- 

FIG.  10. 


THE  LACCOLITE  OF  MT.  MARCELLINA 
(After  W.Cross) 


AM, BANK  NOTE  CC.,N.Y. 


dently  filling  cracks  which  usually  extend  to  a  depth  greater 
than  any  existing  mine-workings.  In  underground  explora- 
tions we  sometimes  come  across  dikes  which  have  failed  to 
reach  the  surface ;  and,  more  rarely,  it  has  been  found  that  the 
lower  end  of  one  of  these  vein-like  bodies  merges  into  the  very 
heart  of  a  large  mass  of  similar  rock.  It  is  inferred  that  every 
dike  emanates  from  some  central  core,  because  a  purely  local 
origin  is  not  conceivable ;  the  conditions  which  induce  liquefac- 
tion and  those  which  compel  the  upthrust  of  the  fused  rock 
are  alike  referable  to  factors  created  by  the  forces  at  work 


*  "  Report  on  the  Geology  of  the  Henry  Mountains,"  1877. 

f  "  The  Laccolitic  Mountain  Groups  of  Colorado,   Utah  and  Arizona." 


Uth 


Annual  Report,  U.  S.  Geol.  Suwey. 


THE    CRIPPLE    CREEK    VOLCANO.  27 

v> 

within  large  masses  of  rock.  The  water  coming  up  through 
a  crack  in  the  ice  is  referred  to  the  body  of  it  beneath  that  ice. 
The  fused  rock  rises  in  the  fractures  caused  by  earth-move- 
ments much  as  the  water  fills  the  cracks  in  the  ice;  that  is,  no 
gaping  crevasse  is  necessarily  formed,  but  the  lava  rises  and 
occupies  the  fracture  as  it  is  formed ;  it  follows  it,  it  does  not 
make  it,  although  the  movement  which  makes  the  crack  and 
the  pressure  which  squeezes  the  lava  into  it  may  both  be  trace- 
able, far  back,  to  a  common  cause. 

The  behavior  of -dikes  often  affords  striking  evidence  of  their 
adaptability  to  the  structure  of  the  rocks  they  traverse.  They 
seek  out  lines  of  least  resistance,  and  thus  frequently  make 
evident  structural  features  which  otherwise  would  have  been 
merely  latent.  The  accompanying  drawing  (Fig.  11)  illus- 
trates this.  It  represents  a  flat  surface  of  granite  (in  West 
Australia)  traversed  by  a  dike  of  dolerite,  which  has  evidently 
utilized  for  its  passage  the  lines  of  fracture  produced  along  a 
sheer-zone  in  the  granite.  The  very  low  conductivity  of  lavas 
(as  of  smelter-slag)  may  explain  their  ability  to  pass  through 
rock-fractures  for  great  distances.  The  edges  of  a  dike  would 
cool  instantly,  but  in  so  doing  would  afford  a  protection  to  the 
central  portion,  the  liquidity  of  which  would  thus  tend  to  be 
maintained. 

The  bulk  of  the  material  thrown  up  by  the  Cripple  Creek 
volcano  was  fragmentary,  and  became  the  great  mass  of 
breccia  now  constituting  the  leading  geological  feature  of  the 
district.  The  earliest  lavas  extruded  were  of  medium  fusi- 
bility :  namely,  andesite,  and  then  phonolite.  On  reaching 
the  surface,  they  formed  streams,  the  exterior  of  which  became 
promptly  chilled  to  a  black-looking  slag,  to  which  escaping 
steam  gave  a  cindery  structure.  The  lava  rolled  down  the 
slope  of  the  volcano  with  the  utmost  slowness,  making  clinking 
sounds  such  as  are  heard  when  the  workmen  empty  the  slag- 
pots  over  the  dump  of  a  smelter.  Such  lava-streams  weather 
very  easily  ;  their  exterior,  by  the  contraction  of  the  surface  due 
to  cooling,  becomes  porous,  and  water  penetrates  into  the  mass 
of  them,  disintegrating  them  so  that  they  are  readily  carried 
away  by  the  rains  of  spring. 

The  last  extrusions  of  the  Cripple  Creek  volcano  were  of 
basalt.  These  were  more  limpid,  and  must  have  formed 


28 


THE    CRIPPLE    CREEK   VOLCANO. 


4     -f 


+    4j       4-+       4-    +    + 


Dike 


Granita 


THE    CRIPPLE    CREEK    VOLCANO.  29 

streams  which  traveled  much  farther  than  the  less  fusible 
phonolite  and  andesite.  The  basalt,  judging  from  the  be- 
havior of  similiar  lava-flows  actually  observed  in  the  Hawaiian 
Islands  and  elsewhere,  would  progress  rapidly  down  the  slopes 
of  the  mountain  and  overwhelm  the  forests  which,  probably, 
clothed  the  lower  portions  of  the  Cripple  Creek  volcano,  setting 
them  on  fire  and  adding  greatly  to  the  aspects  of  destruction 
presented  by  the  scene.  Upon  cooling,  these  basaltic  flows 
would  be  cleft  asunder  by  symmetrical  series  of  cracks  forming 
prismatic  columns  grouped  like  the  pillars  of  a  Gothic  cathedral. 
But  where  they  were  not  protected  by  a  later  covering  of  rock, 
the  ruthless  hand  of  decay  attacked  them  also,  the  frost  of 
many  thousand  years  shivered  the  straight  columns ;  and  the 
freshets  of  spring  swept  the  remnants  into  the  torrents  which 
fe.d  the  Arkansas  river. 

The  successive  periods  of  activity  in  the  life  of  the  Cripple 
Creek  volcano  are  marked  by  the  sequence  of  lavas  extruded. 
This  sequence  is  indicated  by  structural  relations,  the  older  ex- 
trusions being  penetrated  by  the  younger.  But  this  is  not  all. 
The  crystalline  structure  and  the  chemical  composition  of  the 
rocks  resulting  from  the  cooling  and  consolidating  of  the 
successive  lavas  exhibit  differences  which  have  been  found  to  be 
closely  analogous  to  those  presented  by  similar  successions  of 
rock  at  other  volcanic  centers,  both  in  the  United  States  and  in 
Europe.  The  earliest  lava  extruded  by  the  Cripple  Creek  vol- 
cano was  andesite.  Then  came  the  phonolite,  and,  lastly,  the 
basalt.  These  three  rocks  represent  types  which  vary  in  their 
chemical  composition  and  in  their  consequent  fusibility.  Basalt 
fuses  at  about  2250°  F. ;  certain  varieties  fuse  at  about  2000° 
F.  What  is  usually  termed  a  "  white  heat  "  is  equivalent  to  a 
temperature  of  2100°  F*.  The  least  fusible  rocks  are  of  the 
granite  and  trachyte  class ;  they  fuse  with  difficulty  at  about 
2700°  F.  To  the  intermediate  type  belong  the  andesites,  which 
fuse  at  about  2520°  F.f  The  relative  fusibility  of  these  rocks 
is  dependent  upon  the  fusibility  of  their  chief  constituent,  feld- 

*  According  to  the  latest  determinations  by  Henry  M.  Howe.  According  to 
Pouillet's  experiments,  gold  melts  at  2192°  and  silver  at  1832°  F.  See  Eng.  and 
Min.  Journal,  Jan.  20,  1900,  p.  75. 

t  These  are  the  temperatures  derived  from  the  experiments  of  Carl  Barus. 
See  Dana's  Manual  of  Geology,  p.  273. 


30  THE    CRIPPLE    CREEK    VOLCANO. 

spar,  the  variety  in  the  basalts  being  labradorite,  the  most  fusi- 
ble of  the  feldspars.  Moreover,  in  basalt  there  is  present  a 
good  deal  of  augite,  a  still  more  fusible  mineral,  and  a  large 
percentage  of  iron  which,  as  in  smelter-slags,  contributes  di- 
rectly to  fusibility.  The  trachytes  are  largely  made  up  of 
orthoclase,  the  least  fusible  of  the  feldspars.  The  andesites 
are  intermediate  in  composition  and  of  medium  fusibility,  their 
characteristic  feldspar  being  oligoclase. 

This  fusibility  used  to  be  expressed  in  terms  of  "  acid  "  and 
"  basic  character^'  the  rocks  high  in  silica  and  low  in  iron  being 
at  one  extreme,  and  those  low  in  silica  and  high  in  iron  at  the 
other.  But  Dana  has  pointed  out*  that  this  does  not  express  it 
correctly,  fusibility  being  dependent  not  so  much  on  the  per- 
centage of  silica  as  upon  the  amount  of  alkali,  namely,  potash 
and  soda.f  Thus  the  rocks  rich  in  alkaline  feldspars  are  the 
most  fusible.  Free  quartz  exists  in  most  rocks ;  and  the  percent- 
age of  it,  which  is  far  from  uniform  among  the  members  of 
any  particular  type,  increases  the  acid  character  of  the  rock,  so 
that  it  becomes  a  secondary  factor  in  determining  fusibility. 
Similarly  iron  occurs  as  an  oxide  (magnetite)  in  all  rocks,  to  an 
insignificant  degree  in  the  granites,  but  in  the  basalts  and  gab- 
bros  freely,  so  as  to  form  an  important  ingredient,  giving  them 
their  dark  coloring.  This  large  percentage  of  iron  contributes 
to  easy  fusibility ;  indeed,  certain  basalts  are  known  to  become 
so  limpid  that  they  can  be  taken  up  in  a  spoon  attached  to  the 
end  of  a  cane.J 

This  question  of  fusibility  would  be  of  slight  importance 
were  it  not  for  one  interesting  fact,  namely :  it  has  been  ob- 
served in  several  volcanic  regions  that  lava  of  intermediate 
composition,  such  as  andesite,  is  succeeded  by  those  of  the 
extreme  types,  namely,  the  very  alkaline  or  comparatively  non- 
alkaline  rocks,  such  as  basalt  and  rhyolite,  respectively.  This 
was  the  case  at  the  Cripple  Creek  volcano.  It  has  been  in- 
ferred from  these  facts  that  in  the  earlier  stages  of  volcanic 
activity  the  lavas  are  mingled  together  underground,  and  that 
during  the  period  of  eruption  the  heavier  portion  separates 

*  Manual  of  Mineralogy  and  Petrography,  p.  437. 
f  Dana,  Characteristics  of  Volcanoes,  p.  146. 

J  This  was  actually  done  in  the  case  of  the  basaltic  lava  of  Kilauea,  in  Hawaii. 
Coan.  American  Journal  of  Science. 


THE    CRIPPLE    CREEK    VOLCANO.  31 

from  the  lighter,  causing  two  diverse  products  to  be  separately 
emitted. 

Eventually  (it  may  have  been  several  thousand  years  after 
the  first  manifestation  of  activity)  the  volcanic  energies  became 
wearied,  and  lava  ceased  to  appear  at  the  surface.  The  re- 
adjustment of  the  earth's  crust,  at  this  particular  locality,  had 
been  accomplished,  and  a  condition  of  equilibrium  supervened. 
The  lava  sank  beneath  the  level  of  the  crater,  and,  on  cooling, 
plugged  up  the  conduit,  as  was  the  case,  for  instance,  at  the 
Kammerbuhl.*  The  sinking  of  the  lava  may  have  gone  further, 
so  that  the  withdrawal  from  the  upper  part  of  the  mountain, 
formed  by  the  ejections  of  the  volcano,  may  have  caused  ex- 
tensive subsidence  and  created  deep  fissures.  Such  was  the 
case  at  Kilauea  in  1832  and  1840.  f  Those  who  are  engaged 
in  mining  at  Cripple  Creek  are  aware  of  the  existence  of 
numerous  large  cavities  underground,  particularly  in  the  south- 
ern part  of  Bull  hill  and  the  northwestern  portion  of  Battle 
mountain.  In  the  Logan  mine  the  orifice  of  a  very  large 
cavity  was  recently  encountered  while  sinking  the  shaft.  J  The 
sudden  flows  of  water  which  have  embarrassed  some  of  the 
mines  are  due  to  the  unexpected  drainage  of  such  openings. 
It  is  worthy  of  note  that  these  especially  characterize  the 
trachyte-phonolite  and  those  rock-masses  which  represent  the 
lavas  extruded  last. 

After  the  volcanic  energies  had  declined,  there  followed  a 
long  period  of  smothered  activity,  evidenced  by  geysers  and  hot 
springs.  Steam  continued  to  escape,  but  gently.  There  was 
none  of  the  violence  of  the  earlier  period.  Heated  water  ac- 
companied the  steam,  instead  of  fused  rock.  The  hot  lava  still 
existing  at  greater  depth  served  to  give  expansive  force  to  the 
surface  waters  which  found  their  way,  by  seepage,  through 
the  overlying  deposits  of  volcanic  material.  The  steam  and  hot 
water  now  emitted,  at  some  spots  quietly  as  a  thermal  spring 
and  elsewhere  intermittently  as  a  geyser, §  probably  carried  a 

*  Judd's  Volcanoes,  p.  114.     See  also  p.  5  of  this  paper. 

f  Dana's  Characteristics  of  Volcanoes,  p.  124. 

J  The  miners  heard  the  inrush  of  air  caused  when  they  tapped  the  cavity  and 
promptly  left  their  work,  to  go  to  the  surface.  It  is  probable  that  the  pumping 
operations  of  the  neighboring  Portland  mine  had  drained  the  water,  which  at  one 
time  had  filled  the  cavity,  leaving  it  void. 

$  Geyser  is  an  Icelandic  word,  and  means  "gusher."  A  thermal  spring  which 
spouts  or  gushes  out  above  the  surface  is  a  geyser. 


32  THE    CRIPPLE    CREEK    VOLCANO. 

good  deal  of  mineral  matter  in  solution.  A  wonderful  work  is 
accomplished  in  this  quiet  way,  because  such  activities  extend 
over  enormous  periods  of  time.  Professor  Judd  has  shown 
that  the  hot  spring  at  Bath  (England),  although  an  apparently 
unimportant  geological  agent,  brings  daily  to  the  surface 
180,000  gallons  of  water  at  a  constant  temperature  of  120°  F. 
This  spring  was  doing  its  duty  at  the  time  of  the  Roman  in- 
vasion of  England,  and  it  is  estimated  that  since  that  time  it  has 
brought  up,  in  solution,  enough  material  to  form  a  good  sized 
volcanic  cone.*  % 

The  Cripple  Creek  district  exhibits  abundant  evidence  of 
hydrothermal  action.  This  is  particularly  the  case  in  the 
northwestern  part  of  the  mining  area.  The  breccia  of  the 
upper  parts  of  Globe  and  Ironclad  hills,  penetrated  by  the 
workings  of  the  Deerhorn,  Summit,  South  Park,  Plymouth 
Rock  and  other  mines,  is  much  decomposed,  and  has  a  loose, 
crumbly  character.  It  is  seamed  to  an  unusual  degree  with 
irregular  fractures,  lined  with  secondary  minerals,  among 
which  crystalline  gypsum  and  amorphous  kaolin  are  the  most 
common.  In  the  Deerhorn  shaft  there  is  evidence  of  a  more 
definite  kind.  At  a  depth  of  240  feet  the  shaft  cuts  into  a 
mass  of  gypsum,  and  from  that  point  to  the  bottom,  575  feet 
below  the  surface,  it  has  been  sunk  in  the  midst  of  what 
appears  to  be  a  series  of  extinct  thermal  springs.  The  accom- 
panying drawing,  Fig.  12,  will  illustrate  the  occurrence. 

The  workings  are  very  extensive  in  a  direction  at  right- 
angles  to  the  plane  of  the  section  followed  by  the  illustration, 
and  connect  with  the  adjoining  mines.  Breccia  and  tuff  com- 
pose the  prevailing  rock.f  No  distinct  dikes  are  visible  near 
the  Deerhorn  shaft;  it  is  probable,  judging  from  the  com- 
position of  the  breccia  at  several  points,  that  several  intru- 
sions do  exist,  but  that  they  have  been  so  shattered  in  place  as 
to  be  scarcely  distinguishable  from  the  original  breccia  which 
surrounds  them.  At  the  third  level,  and  at  the  succeeding 
levels,  there  are  three  distinct  narrow-pointed  cones  of  com- 

*  Page  21 9  of  Volcanoes. 

f  The  breccia  was  found  by  Professor  Kemp  to  contain  undoubted  fragments 
of  kaolinized  granite,  decomposed  orthoclase  being  easily  recognizable.  The 
breccia  of  Cripple  Creek,  although  fragmentary  andesite  predominates,  every- 
where exhibits  a  scattering  of  granite  particles,  which  in  places  become  so  numer- 
ous as  to  give  it  a  truly  granitic  character. 


THE    CRIPPLE    CREEK    VOLCANO. 


33 


FIG   12. 


Deerhorn  Shaft 


Gypsum  Breccia 

AN  EXTINCT  THERMAL  SPRING,  CRJPPLE  CREEK. 

pact  white  gypsum  which,  at  15  to  25  feet  from  their  apex, 
graduate   into  chimney-like  masses   of  breccia   cemented   by 

3 


34  THE    CRIPPLE    CREEK    VOLCANO. 

crystalline  gypsum.  At  the  sixth  level  there  is  a  fourth  of 
these  occurrences.  Others,  which  do  not  happen  to  have  been 
intercepted  by  the  workings  of  the  mine,  may  exist  in  the 
vicinity. 

Iron  pyrites  is  found  in  the  gypsum ;  it  occurs  as  a  scattering 
of  coarse  crystals  in  the  upper  portion,  and  finely  disseminated 
lower  down.  The  white  gypsum  carries  patches  which  are 
stained  pink  by  'fluorite.  The  surrounding  breccia  is  every- 
where traversed  by  color-bands  due  to  layers  of  gypsum,  man- 
ganese oxides,  and  iron  ocher.  Scattered  through  the  vicinity, 
but  parallel  to  the  group  of  columns  above  described,  there  are 
patches,  as  well  as  seams,  of  fluorite  sand,  consisting  of  parti- 
cles of  crystalline  silica  stained  purple  by  admixture  with  fluor- 
spar. The  upper  levels  also  show  bands  of  a  white  unctuous 
clay,  named  "  Chinese  talc  "  by  the  miners.  This  is  pure  kao- 
lin,* derived  from  the  decomposition  of  the  feldspar  in  the 
andesite  fragments  composing  the  bulk  of  the  breccia.  The 
latter  is  in  a  crumbly  condition,  its  character  being  suggested 
by  the  fact  that  in  driving  the  levels  only  a  pick  is  needed,  the 
ground  requiring  no  blasting.  Beyond  the  central  portion, 
which  has  structural  lines  sympathetic  to  the  arrangement  of 
the  columns  of  gypsum,  the  breccia  is  still  stained  and  dis- 
integrated for  a  great  distance,  and  in  places  exhibits  sug- 
gestions of  the  neighborhood  of  other  thermal  conduits. 

There  can  be  no  doubt  as  to  the  nature  of  these  masses  of 
gypsum.  Thermal  springs  which  have  become  extinguished 
are  marked  by  just  such  accumulations  of  lime,  although  the 
carbonate  is,  under  such  circumstances,  more  common  than  the 
sulphate. f  The  flows  of  hot  water  encountered  in  the  deep 

*  The  following  is  Dr.  Hillebrand's  analysis,  made  by  him  for  Prof.  Penrose. 
See  page  128  of  the  Report  on  "The  Geology  and  Mining  Industries  of  the  Cripple 
Creek  District,"  U.  S.  Geological  Survey,  Itith  Ann.  Rep.  Part  II. 

Silica,    .  .  ,        .  .  .  :  •'  V  •         •         •  -  45.08 

Alumina,  .  .        .  .  J  •      .         .         .        .  .  31.83 

Ferric  oxide,  .        .  .  .  '.       V   .     .         .  .  .95 

Lime,     .  .....  .  ...         .  .  1.76 

Magnesia,       .  ,»"'"•  .  .  .,,•„,.•.     '  '.».'..  .  .59 

Potash,.  f.' '  "'' J. '"'/ ."  'v ;.  ""'".  '" ;-.'";"': '.  '  •'/ "'  -'  .  "'  .  .14 

Water,    .  ',  ...  '     .  .  .  .      „.        .        .  .  19.96 

100.31 
f  Siliceous  deposits  characterize  geysers. 


THE    CRIPPLE    CREEK    VOLCANO.  35 

workings  of  the  Comstock  carried  a  notable  percentage  of  gyp- 
sum. Last  April,  while  examining  certain  copper-mines  near 
Hawthorne,  in  Nevada,  the  writer  came  across  a  group  of  sim- 
ilar vents,  marking  the  site  of  former  thermal  springs.  The 
conduits,  in  this  case,  occurred  in  lime-shales,  and  were  still 
open  to  a  considerable  depth,  as  was  proved  by  dropping  stones 
into  them.  They  were  surrounded  by  a  compact  chimney  of 
carbonate  of  lime,  which  had  also  overspread  the  enclosing 
rock. 

Recurring  to  the  conditions  observed  in  the  Deerhorn  shaft, 
it  would  seem  that  the  rising  hot  waters,  in  their  approach  to 
the  surface,  were  unable  to  maintain  a  defined  channel  through 
the  breccia  higher  than  the  level  marked  by  the  tops  of  the 
cones  of  gypsum.  This  might  be  caused,  first,  by  the  fact  that 
the  vapors  ascending  above  the  subterranean  springs  disinte- 
grated the  breccia  so  as  to  destroy  its  cohesion,  and  changed  it 
from  a  compact  rock  to  loose  material.  The  most  potent  factor, 
however,  was  probably  the  diffusion  of  the  ascending  waters 
into  the  drainage  of  the  surface,  the  effect  of  which  would  be 
encountered  at  this  horizon.  The  condition  of  the  breccia  and 
the  wide  area  which  has  undergone  disintegration  favor  this 
view. 

It  is  in  accord  with  facts  observed  in  other  regions  that  the 
vents  which  permitted  the  emission  of  lava-flows  should  be  in 
one  part  of  the  volcanic  area  (in  this  case  the  southern  portion) 
while  the  escape  of  hot  waters  which  marked  the  time  when 
the  volcanic  energies  were  waning  should  have  occurred  in 
another  part,  in  this  case  the  northern  and  northeastern. 
The  lava  had  healed  lines  of  weakness ;  it  had  cemented  the 
fractures  produced  by  the  earlier  paroxysmal  efforts  of  the  vol- 
cano ;  and  therefore  the  thermal  waters  found  a  better  chance  of 
exit  elsewhere.  With  the  hot  waters  which  found  their  way  to 
the  surface  during  the  closing  period  of  the  volcanic  cycle  there 
were  emanations  of  gas.  Sulphuretted  hydrogen  was  probably 
emitted,  sulphurous  acid  gas,  and,  in  all  likelihood,  carbonic 
acid  gas  also,  although  not  all  of  these  were  to  be  found  at  one 
place  or  at  one  time.  The  volcano  had  now  reached  the  "  sol- 
fatara"  stage.*  These  acid  gases  played  an  important  part  in 

*  "Solfatara"  is  from  the  Italian  "solfo,"  meaning  sulphur.  It  is  a  name 
given  to  one  of  the  small  volcanoes,  near  Naples,  which  is  in  a  condition  such 
as  marks  the  dying  out  of  volcanic  activity. 


36  THE    CRIPPLE    CREEK    VOLCANO. 

altering  the  volcanic  rocks,  and  were,  possibly,  a  factor  in  the 
process  of  ore-deposition  which  was  beginning.  The  vapor  of 
hydrofluoric  acid  was  also  among  the  agencies  at  work.  This 
is  inferred  from  the  large  amount  of  fluorite,  the  fluoride  of 
calcium,  which  occurs  all  over  the  district,  and  more  especially 
in  the  gold-bearing  lodes.  Fluorite  is  not  common  in  volcanic 
regions,  although  it  is  found  in  the  lava  of  Vesuvius.  The 
action  of  hydrofluoric  acid  on  feldspars  containing  lime  would 
form  fluorite.  It  would  also  convert  gypsum  in  a  similar  way. 
Fouque  has  shown  that  the  action  of  hydrofluoric  acid  in  the 
liquid  state  is  to  decompose,  first,  uncrystalline  silicates  or 
glasses,  then  feldspar  and  other  acid  silicates,  then  quartz,  and 
lastly,  basic  silicates.  Whether  the  vapor  of  hydrofluoric  acid 
would  act  in  the  same  way  is  uncertain,  although  it  is  possible 
that  in  this  case  quartz  might  be  attacked  in  preference  to  the 
feldspar.  This  is  a  matter  of  interest,  because  in  examining 
specimens  of  granite  which  have  been  converted  into  ore  (by 
the  addition  of  gold-bearing  tellurides)  it  is  observable  that  the 
original  quartz  of  .the  granite  has  been  attacked  while  the 
orthoclase  remains  comparatively  fresh. 

This  last  stage  of  the  Cripple  Creek  volcano  is  of  great 
importance  to  the  mining  geology  of  the  region.  It  extended 
over  an  enormous  period,  coinciding,  roughly  speaking,  with 
that  which  has  elapsed  since  the  time  to  which  is  ascribed  the 
first  evidence  of  the  existence  of  the  human  genus,  and  it 
afforded,  to  an  unusual  degree,  those  particular  conditions  which 
are  considered  to  favor  the  deposition  of  precious  ores.  During 
this  time,  also,  the  breccia,  with  its  finer  portions,  the  tuff, 
became  solidified.  The  pressure  of  the  overlying  masses  of 
lava  which  at  one  time  covered  it,  and  the  chemical  solutions, 
which  deposited  fresh  crystalline  substances  in  the  interspaces, 
converted  the  scoriaceous  material  into  a  compact  mass, 
which  eventually  became  solid  rock  as  we  now  see  it.  The 
cooling  of  the  intrusive  bodies  of  lava  caused  them  to  contract, 
and  thus  developed  lines  of  weakness  along  which  the  ener- 
gies of  the  volcanic  center  developed  fractures  permitting  the 
subsequent  prolonged  circulation  of  underground  waters.  The 
readjustment  of  this  particular  portion  of  the  earth's  exterior, 
which  followed  the  cessation  of  volcanic  eruptions,  and  the 
partial  settling  of  the  entire  mass  forming  the  Cripple  Creek 


THE    CRIPPLE    CREEK    VOLCANO.  37 

volcano,  must  have  formed  an  extensive  system  of  ruptures, 
which  afforded  lines  of  maximum  porosity  along  which  the 
gold-bearing  solutions  found  passage-ways.  Thus  the  hot 
waters  which  are  supposed  to  dissolve  out  the  metals  from  the 
deep-seated  rocks  were  permitted  to  ascend  toward  the  surface, 
where  the  release  from  pressure  and  the  lowering  of  tempera- 
ture forced  them  to  precipitate  their  contents. 

The  activity  of  the  geysers  ceased ;  the  warmth  of  the  water 
bubbling  from  the  springs  gradually  diminished ;  and  at  length 
the  last  vestige  of  the  volcanic  fires  passed  away.  The  moun- 
tain became  as  cold  as  the  snow  which  mantled  it  each  winter, 
and  as  still  as  the  darkness  enshrouding  it  nightly. 


S  OBJECT  TO  REVISION. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Lodes  of  Cripple  Creek. 

BY  T.    A.  RICKARD,   DENVER,  COLORADO. 
(New  Haven  Meeting,  October,  1902.) 

A.  INTRODUCTORY. 

IN  a  former  paper*  the  writer  has  described  the  essential 
features'  of  the  general  geology  of  the  Cripple  Creek  region. 
In  the  present  account  it  is  intended  to  examine  into  the  oc- 
currence of  the  ores,  the  value  of  which  has  made  this  district 
the  most  important  among  existing  American  gold-fields.  The 
production  of  Cripple  Creek  from  its  discovery,  in  1891,  to  the 
close  of  1901,  has  reached  a  valuation  of  fully  $125,000,000. 
During  the  past  year  (1901)  the  output  amounted  to  $17,285,- 
470.  In  1900  it  was  $18,174,681. 

The  first  discoveries,  which  led  to  the  development  of  the 
district,  were  made  in  the  spring  of  1891,  but  it  was  not 
until  1893  that  vigorous  work  was  commenced.  A  great  im- 
petus was  then  given  to  the  exploration  for  gold  on  account 
of  the  sudden  drop  in  the  market-price  of  silver,  caused  by 
the  closing  of  the  Indian  mints  in  the  summer  of  that  year. 
This  induced  an  energetic  population  from  the  older  silver- 
mining  camps  of  Colorado  to  go  to  the  new  gold-field,  which 
was  then  beginning  to  attract  attention.  Prospecting,  at  first, 
was  hindered  by  the  comparative  absence  of  outcrops,  due  to 
the  fact  that  the  surface  of  the  hills  is  covered  with  a  consid- 
erable thickness  of  shattered  rock,  resulting  from  the  action  of 
frost  at  a  high  altitude ;  but  so  much  indiscriminate  digging 
was  done  that  a  number  of  rich  veins  were  uncovered,  and  this 
stimulated  the  search  for  others.  The  advanced  condition  of 
the  mining  industry  of  Colorado  offered  unusual  facilities  for 
exploration  and  reduction ;  progress  was  therefore  rapid,  with 
the  result  that  the  district  soon  achieved  great  prominence. 

*  "The  Cripple  Creek  Volcano,"  Trans. t  xxx.,  367-403.  It  is  proper  that 
reference  should  also  be  made  to  the  more  authoritative  monograph  of  the  U.  S. 
Geological  Survey,  namely,  "  Geology  and  Mining  Industries  of  the  Cripple 
Creek  District,  Colorado,"  by  Whitman  Cross  and  K.  A.  F.  Penrose,  Jr.  1895. 


Z  THE    LODES    OF    CRIPPLE    CREEK. 

B.  GEOLOGICAL  CHARACTER  OF  THE  DISTRICT. 

The  geological  environment  of  the  gold-bearing  veins  can  be 
outlined  briefly.  The  district  occupies  the  ground-floor  of  a 
volcano,  the  superstructure  of  which  has  been  removed  by  ero- 
sion. This  basal  wreck  of  material  erupted  during  the  Tertiary 
period  now  survives  as  a  complex  of  volcanic  rocks,  tilling  the 
hollows  and  occupying  the  plug  of  a  basin  which  is  surrounded 
by  the  granite  of  Pike's  Peak.  The  volcanic  area  of  Cripple 
Creek  occupies  about  nine  square  miles,  and  consists,  for  the 
most  part,  of  breccia,  in  which  andesite  predominates.  Pene- 
trating the  breccia  in  every  direction  are  numerous  dikes, 
composed  of  various  rocks,  those  of  basalt  and  phonolite  being 
the  most  notable,  on  account  of  their  close  association  with 
the  occurrence  of  ore. 

The  mine-workings  have  reached  a  maximum  depth  of  1400 
ft.  Added  depth  appears  to  have  affected  the  persistence  of 
the  ore  to  the  same  extent  as  experience  elsewhere  would  lead 
one  to  expect.  The  veins  situated  near  the  edge  of  the  breccia 
have  in  several  cases  been  followed  downward  in  their  penetra- 
tion of  the  underlying  granite,  and  it  has  been  demonstrated  that 
some  of  the  ore-bodies  have  continued  from  the  upper  into  the 
lower  geological  horizon.  The  distribution  of  these  ore-bodies 
offers  the  same  perplexing  problems  as  in  other  gold-fields.  Ex- 
tensive developments,  due  to  very  successful  mining,  have,  how- 
ever, afforded  a  great  deal  of  interesting  evidence,  the  consid- 
eration of  which  may  contribute  toward  the  better  understand- 
ing of  the  economic  geology  of  the  district. 

The  mines  exhibit  examples  of  a  great  diversity  of  lode- 
structure.  This  diversity  is  mainly  traceable  to  the  complexity 
of  the  enclosing  rocks.  The  variations  in  ore-occurrence  due 
to  this  fact  explain  the  vicissitudes  which  marked  the  early 
history  of  the  district,  and  the  recognition  of  them  should  pro- 
mote the  success  of  future  exploratory  work. 

During  the  past  five  years,  while  examining  a  dozen  of  the 
principal  mines,  the  writer  has  gathered  many  examples  of 
vein-structure  which  are  herewith  submitted  as  testimony  bear- 
ing upon  the  ever-fascinating  problem  of  ore-occurrence.  As 
a  poor  witness  may  sometimes  furnish  a  good  lawyer  with  an 
illuminating  bit  of  evidence,  so  the  writer  hopes  that  this  testi- 
mony may  be  of  service  to  the  geological  philosophers  who  are 
engaged  in  the  study  of  ore-deposits. 


THE    LODES    OF    CRIPPLE    CREEK. 


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4  THE    LODES    OF    CRIPPLE    CREEK. 

C.  A  TYPE  OF  LODE-STRUCTURE. 

A  small  section  of  a  single  vein  will  sometimes  typify  the 
lode-structure  of  an  entire  region.  Such  I  believe  to  be  the 
case  in  the  occurrence  which  is  illustrated  in  Fig.  1.  It  repre- 
sents the  vertical  section  of  a  portion  of  the  Independence  vein 
as  it  appeared  just  south  of  the  station  at  the  second  level  from 
the  No.  1  shaft.  The  scale  indicates  that  the  space  covered  is 
about  10  ft.  high  by  16  ft.  wide.  The  country-rock  is  the  pink, 
coarsely  crystalline  Pike's  Peak  granite ;  the  vein,  A  K,  L  C, 
appears  as  a  band  of  iron-stained,  decomposed  granite  along- 
side of  a  phonolite  dike,  A  B,  C  D,  which  throws  out  a 
nearly  horizontal  tongue,  E  F,  G  H,  into  the  rock  on  the 
west.  This  offshoot  from  the  dike  is  crossed  by  the  vein,  and  it 
affects  the  distribution  of  the  ore.  Thus,  while  the  decom- 
posed gold-bearing  granite,  constituting  the  lode,  is  about  1-1} 
ft.  wide  both  above  and  below  this  intrusion  of  phonolite,  it  is 
broken  up  at  the  place  of  crossing  into  a  few  stringers  cutting 
through  the  phonolite ;  so  that,  while  the  lode  maintains  its 
continuity,  it  does  so  with  difficulty.  An  important  feature  of 
the  section  is  the  evidence  obtainable  as  to  the  relative  age  of 
the  phonolite  and  the  joint-planes  in  the  granite.  The  pho- 
nolite is,  of  course,  younger  than  the  granite  which  it  pene- 
trates. But  this  is  not  all ;  it  is  also  apparent  that  the  joints  in 
the  granite  are  more  recent  than  the  dike.  Observe  how  the 
joint-planes,  E  F  and  G  H,  cut  through  the  protruding  sinuosi- 
ties of  the  outer  edge  of  the  phonolite.  It  remains  to  add  that 
there  is  a  distinct  division,  but  no  selvage,  between  the  hang- 
ing-wall, A  C,  of  the  vein  and  the  dike  which  it  accompanies, 
while  on  the  other  side,  K  L,  the  vein  is  not  marked  by  any 
clear  line,  but  graduates,  by  the  lessening  of  the  evidences  of 
decomposition,  into  the  outer  granite.  The  east  wall,  B  D,  of 
the  dike  exhibits  a  marked  selvage,  and  it  is  also  accompanied 
by  traces  of  ore.  On  the  joint-plane,  G  H,  which  is  nearly 
horizontal,  there  is  a  slight,  but  evident,  selvage. 

The  story  told  by  this  section  is  that  the  phonolite  penetrated 
the  granite;  that,  subsequently,  a  line  of  fracture  was  estab- 
lished alongside  the  phonolite ;  that  this  afforded  a  passage-way 
for  ore-bearing  solutions ;  that  the  impregnation  of  ore  was  less 
where  the  solutions  passed  through  the  protruding  tongue  of 
phonolite,  because  there,  the  rock  being  closer-grained  and 


THE    LODES    OF    CRIPPLE    CREEK. 


more  fissile  than  the  granite,  it  was  broken  by  a  very  few  de- 
cided cracks,  rather  than  by  an  irregular  multiple  fracturing 
such  as  determined  the  diffused  mineralization  constituting  the 
lode  in  the  granite;  further,  it  is  evident  that  the  jointing  of 


FIG.  2 


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I     VyV(     PHONOLITE. 


3 

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the  granite,  due  to  a  condition  of  strain,  must  have  occurred 
subsequent  to  the  intrusion  of  the  phonolite,  because  the  joints 
cut  through  the  edges  of  the  phonolite  ;*  finally,  it  is  rendered 

*  Of  course  it  is  possible  that  the  cracks  through  the  phonolite  are  merely  the 
prolongation  of  the  joints,  and  that  this  extension  of  the  latter  may  have  been 
of  later  origin  ;  but  this  is  not  my  interpretation  of  the  evidence  as  I  have  seen  it. 


6  THE    LODES    OF    CRIPPLE    CREEK. 

very  probable  that  the  jointing  of  the  granite  and  the  fractur- 
ing now  identified  with  the  lode  were  contemporaneous,  both 
being  the  result  of  mechanical  stresses  connected  with  the 
earth-movements  which  followed  the  last  stages  of  volcanic 
activity  in  the  district. 

D.  GENERAL  CHARACTERISTICS  OF  THE  VEINS. 

The  foregoing  example  will  serve  as  a  text  for  a  preliminary 
statement.  The  lodes  of  Cripple  Creek  are  essentially  lines  of 
fracture  accompanied  by  a  variable  width  of  rock,  the  constitu- 
ents of  which  have  undergone  replacement  by  fluorite,  quartz, 
pyrite  and  other  gangue,  together  with  gold-bearing  tellurides. 
The  width  and  distribution  of  the  ore  depends  upon  the  extent 
and  character  of  the  fracturing ;  the  study  of  the  latter  is  there- 
fore of  vital  importance  to  the  miner.  Owing  to  the  number 
of  volcanic  rocks  occurring  in  the  district,  the  veins  differ 
greatly  in  appearance ;  but  this  difference  is  traceable  to  diverse 
structural  conditions  rather  than  to  diversity  of  origin.  In  all 
the  lodes  which  I  have  examined,  the  ore  is  essentially  rock  in 
place,  however  much  altered ;  the  lodes  are  to  be  regarded  as 
bands  of  replacement,  rather  than  the  filling  of  open  fissures  or 
crevices ;  nor  is  there  any  departure  from  the  rule  that  the 
lodes  were  formed  during  a  late  period  in  geological  history, 
for  the  ore  is,  in  every  case,  as  far  as  I  know,  subsequent  to  the 
intrusion  of  the  eruptives  which  penetrate  the  breccia,  itself  of 
late  Eocene  or  early  Miocene  age.  While  these  eruptives  cut 
across  each  other  and  thereby  evidence  their  relative  succession 
in  geological  time,  they  do  not  appear  to  cut  across  the  ore- 
veins,  which,  on  the  contrary,  pursue  their  course  amid  varying 
petrographic  conditions,  unchecked  but  not  unchanging,  for  to 
the  changes  due  to  this  variable  rock-environment  we  owe  the 
extremely  interesting  variations  in  ore-occurrence. 

The  lodes  have  originated  from  lines  of  fracture  formed  sub- 
sequent to  all  the  members  of  that  volcanic  complex  which  con- 
stitutes the  gold-field.  These  fractures  are  the  outward  mani- 
festation of  lines  of  weakness,  or  of  such  comparative  weakness 
as  is  the  equivalent  of  least  resistance ;  therefore,  it  is  not  at  all 
surprising  that  the  veins  frequently  follow  the  planes  of  contact 
between  rocks  which  are  unlike  in  hardness,  and  especially  the 
very  close-grained  eruptives  when  these  traverse  the  coarse- 
textured  breccia. 


THE    LODES    OF    CRIPPLE    CREEK. 


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8  THE    LODES    OF    CRIPPLE    CREEK. 

For  this  reason  phonolite  is  closely  related  to  the  occurrence 
of  ore, — so  much  so,  indeed,  as  to  be  often  confounded  with  the 
origin  of  that  ore.  The  later  dikes  of  basalt  are  also  notably 
connected  with  important  lodes.  It  is  possible  to  generalize 
further  and  state  that  the  dikes,  especially  the  very  numerous 
dikes  of  phonolite,  spread  outward  toward  the  edges  of  the 
volcanic  area,  and,  as  a  consequence,  the  strike  of  the  principal 
veins  also  has  a  radiated  distribution.  The  latter  are  dependent 
in  their  strike  upon  structural  relations  coincident  with  the 
dike  system,  the  arrangement  of  which  points  to  the  approxi- 
mate position  of  the  volcanic  vent,  or  vents,  supposed  to  be 
situated  somewhere  in  the  central  portion  of  the  district. 

From  these  preliminary  considerations  it  is  evident  that  the 
study  of  the  district,  from  the  point  of  view  of  the  miner,  re- 
solves itself  into  the  endeavor  to  understand  the  structural  re- 
lations of  the  ore-deposits  as  affected  by  the  fracturing  of  the 
rocks.  Questions  of  origin  may  be  of  greater  interest,  because 
they  appeal  to  the  scientific  imagination,  but  they  do  not  have 
any  direct  bearing  on  the  economics  of  mining.  To  those  who 
conduct  mining  operations  it  is  not  so  much  a  question  of 
"  Where  did  the  gold  come  from  ?"  as  "  What  are  the  condi- 
tions which  determine  the  distribution  of  it  among  the  rocks 
now  penetrated  by  mine-workings?"  Therefore,  the  patient 
deciphering  of  complicated  systems  of  fracture  will  be  of  more 
immediate  help  to  the  miner  than  the  broad  philosophic  con- 
siderations which  render  the  science  of  ore-deposits  so  fascinat- 
ing to  all  of  those  who  are  interested,  even  indirectly,  in 
mining. 

Before  discussing  the  matter  any  further  it  will  be  well  to 
pass  in  review  more  of  the  evidence  afforded  by  the  examina- 
tion of  the  lodes  as  seen  underground.  For  the  sake  of  con- 
venience, it  is  considered  advisable  to  divide  the  lodes  accord- 
ing to  their  encasing  rock,  which  is  also  their  matrix. 

E.  LODES  IN  GRANITE. 

The  granite  which  surrounds,  and  partially  underlies,  the 
breccia  of  the  volcanic  area  of  Cripple  Creek  forms  a  part  of 
the  mass  of  Pike's  Peak,  the  great  mountain  which  overlooks 
the  district  from  the  northeast,  and  has  given  its  name  to  the 
rock.  The  country  near  the  mines,  however,  is  not  the  same  as 


THE    LODES    OF    CRIPPLE    CREEK. 
FIG.  6. 


VKv'^yi;    1    .- 


Anaconda  Lode  as  seen  in  an  Open  Cut  in  1897. 


10  THE    LODES    OF    CRIPPLE    CREEK. 

the  Pike's  Peak  granite,  orthoclase  replacing,  to  a  large  extent, 
the  microcline  of  the  typical  rock.  The  Cripple  Creek  granite 
may  be  described  as  a  pink,  rather  coarsely  crystalline  rock, 
the  most  prominent  constituents  of  which  are  biotite  (black 
rnica)  and  orthoclase  (feldspar),  the  latter  occurring  in  large, 
tabular  crystals.  The  color  of  the  rock  is  due  to  that  of  the 
orthoclase  which  has  been  stained  red  by  iron  oxide.  Flu- 
orite  occurs  sparingly,  but  it  is  interesting  on  account  of  its 
association  with  the  ores  of  the  district.  In  different  portions 
of  the  district  the  granite  presents  variations,  the  most  im- 
portant of  which  is  a  very  fine-grained  rock  that,  in  the  form 
of  dikes,  penetrates  the  coarser  variety,  and  is  evidently  of 
more  recent  date  than  the  basal  rock  of  the  region.* 

Fig.  2  illustrates  a  gold-bearing  lode  in  granite.  It  repre- 
sents the  heading  of  the  160-ft.  level  in  the  Hallett  and  Ham- 
burg claims,  near  Victor,  as  seen  in  April,  1897.  The  ore  ap- 
pears as  an  ill-defined  band,  B  B,  about  1  ft.  wide,  which  is 
wholly  in  granite,  but  at  the  same  time  is  only  2  ft.  distant  from 
a  large  phonolite  dike,  A  A.  The  alteration  of  the  granite, 
which  marks  the  course  of  the  ore,  follows  a  series  of  short, 
overlapping  seams,  parallel  to  the  line  of  the  dike,  and  also  ex- 
tends into  the  surrounding  rock  along  the  cross-joints,  C  C. 
The  width  of  2  ft.  of  granite  which  separates  the  vein  from  the 
dike  exhibits  partial  alteration  along  the  seams,  D  D,  and  car- 
ries a  feeble  scattering  of  ore.  The  granite  under  the  vein  is 
fresh  and  unaltered.  In  the  ore-bearing  rock  the  mica  is  nota- 
bly absent,  the  granite  is  honeycombed  by  decomposition,  and 
of  the  two  constituent  feldspars,  oligoclase  and  orthoclase, 
the  former  is  kaolinized.  Iron  pyrite  bespatters  the  gold- 
bearing  portion,  and,  by  its  partial  oxidation,  stains  it  dark  red. 

Fig.  3  exhibits  the  Independence  lode  in  the  Washington 
claim,  which  is  a  portion  of  the  Stratton's  Independence  prop- 
erty. The  lode,  which  farther  north  traverses  the  breccia  and 
is  closely  associated  with  a  phonolite  dike,  is  seen  here  as  a 
band  of  decomposed  granite  subdivided  equally  by  a  central 
thread  of  quartz.  The  ore  is  essentially  granite.  The  por- 
tion A  C,  D  F,  is  4  ft.  wide,  and  carries  a  little  over  3  ounces 


*  This  is  discussed  by  Whitman  Cross  in  "Geology  and  Mining  Industries  of 
the  Cripple  Creek  District,  Colorado,"  U.  8.  Geol.  Survey,  page  23. 


THE    LODES    OF    CRIPPLE    CREEK.  11 

of  gold  per  ton.  The  width  of  4  ft.  which  carries  gold,  and 
is  therefore  ore,  has  no  parting  or  wall  separating  it  from  the 
outer  rock,  which  is  granite,  and  is  regarded  as  waste,  but  is 
distinguished  from  the  latter  in  many  ways.  The  outer  granite 
is  fresh  and  unaltered,  exhibiting  with  great  clearness  its  con- 
stituent minerals,  reddish  quartz,  black  .biotite-mica  and  pink 
orthoclase-feldspar.  The  inner  gold-bearing  rock  is  much 
altered  by  decomposition  and  replacement;  the  orthoclase 
alone  appears  to  have  survived  the  general  destruction;  the 
mica  has  been  removed,  and,  in  its  stead,  chlorite  can  be  seen 
in  green  patches ;  the  original  crystalline  quartz  is  largely 
gone,  and  the  presence  of  purple  fluorite  suggests  that  hydro- 
fluoric acid  may  have  been  a  primary  agent  in  that  removal ; 
secondary  hydrous  quartz  fills  many  of  the  interstices  between 
the  crystalline  constituents  of  the  rock;*  in  iron-stained  cavi- 
ties free  gold  can  be  seen  by  the  aid  of  a  pocket-lens,  and  the 
gold  is  observed  to  have  the  dark,  lusterless  appearance  which 
characterizes  it  when  derived  from  the  oxidation  of  tellurides. 
The  entire  width  of  this  gold-bearing  decomposed  granite  is 
heavily  iron-stained  by  the  oxides  resulting  from  the  disintegra- 
tion of  the  small  crystals  of  iron  pyrite,  which  can  still  be 
seen,  in  an  unaltered  condition,  scattered  throughout  the  same 
lode,  at  lower  levels.  In  the  center  of  the  band  of  ore  there  is 
a  distinct  parting,  B  E,  which  is  separated  from  a  persistent 
thread  of  white  quartz,  only  about  a  quarter  of  an  inch  in 
width,  by  a  slight  selvage  of  red  clay.  At  a  distance,  the  lode 
appears  as  a  distinct  broad  band  of  iron-stained  granite,  and  it 
is  only  by  closer  examination  that  the  boundaries  of  it  are  seen 
to  consist,  not  of  "  walls  "  or  of  any  such  evident  demarkation, 
but  merely  of  a  transition  from  decomposed  into  undecom- 
posed  granite. 

The  Independence  vein  is  illustrated  again  in  Fig.  4,  which 
was  obtained  on  the  same  level  as  Fig.  3,  but  300  ft.  farther  to 
the  north,  where  the  vein  lies  against  a  phonolite  dike,  A  B— 

*  This  description  is  founded  on  the  examination  of  hand-specimens  by  the 
aid  of  a  pocket-lens.  To  those  who  desire  to  go  into  the  matter  further,  there  is 
the  detailed  description  of  Mr.  Lindgren,  together  with  microscopic  sections  of 
this  very  ore  (made  from  specimens  which  I  gave  to  Mr.  Emmons  in  1900),  to  be 
found  in  that  most  important  contribution  entitled  "  Metasomatic  Processes  in 
Fissure- Veins, "  by  Waldemar  Lindgren,  Trans.,  xxx.,  578-692,  especially 
page  655. 


12  4  THE    LODES    OF    CRIPPLE    CREEK. 

D  E.  The  thread  of  quartz,  shown  at  B  E  in  Fig.  3,  is  to  be 
seen  again  as  a  larger,  but  less  regular  seam,  B  E,  in  Fig.  4.  In 
this  case  it  is  characterized  by  cavities,  or  "  vughs,"  as  the 
miners  call  them,  which  gave  evidence,*  at  the  time  they  were 
first  encountered  by  the  workings,  that  they  had  served  as 
water-holes  along  a  line  of  underground  circulation.  This 
may  be  considered  as  marking  the  line  of  the  original  fracture 
which  determined  the  course  of  the  lode.  In  Fig.  3  it  was  in 
the  center  of  the  ore ;  in  Fig.  4  it  marks  the  western  limit,  and 
separates  the  ore-bearing  granite  from  the  phonolite.  The  lat- 
ter is  20  inches  wide,  and  regular.  The  lode  consists,  as  in  the 
preceding  instance,  of  highly-altered  granite,  which  is  richest 
along  the  contact  with  the  dike,  and  shades  off  eastward  (from 
B  E  toward  C  F)  along  an  irregular  wavy  line,  C  F,  which  in 
no  case  has  any  of  the  characteristics  of  a  "  wall "  or  defined 
separation  between  what  is  gold-bearing  ore  and  what  is  barren 
rock. 

These  characteristics  are  repeated  in  other  sections  which  I 
have  sketched  underground.  The  lodes  in  the  granite  are  fre- 
quently remarkable  for  absence  of  definition,  as  was  instanced 
in  Fig.  4,  this  being  due  to  the  evenly  granular  texture  of  the 
rock.  Within  the  zone  of  oxidation  the  boundaries  of  a  gran- 
ite lode  are  made  manifest  by  the  red-brown  stain,  due  to  the 
decomposition  of  iron  pyrite ;  but  below  the  zone  of  surface- 
waters  it  becomes  difficult  to  distinguish  country- rock  from  ore 
without  frequent  assays.  When  the  granite  has  undergone 
impregnation  it  is  usually  porous,  by  reason  of  the  removal  of 
the  microcline  and  some  of  the  quartz  of  the  original  rock. 
Whatever  biotite,  hornblende  and  epidote  it  contained  are  ab- 
sent from  the  ore,  and  their  decomposition-product,  chlorite,  is 
in  evidence.  Microscopic  sectionsf  indicate  that  secondary 
valencianite  (a  form  of  orthoclase  feldspar)  and  sericite  (hy- 
drous mica)  have  been  formed,  and  that  iron  pyrite,  fluorite 
and  the  tellurides  have  been  deposited  within  the  cavities  pro- 
duced by  the  removal  of  parts  of  the  granite,  and  also  along 
the  cracks  which  traverse  the  rock.  Occasional  specimens,  ob- 
tained from  the  stopes,  exhibit  these  changes  on  a  scale  visible 


*  By  containing  water  and  by  being  lined  with  slime. 

f  See  Lindgren,  Trans.,  xxx.,  656,  and  Genesis  of  Ore-Deposits,  p.  576. 


THE    LODES    OF    CRIPPLE    CREEK.  18 

without  any  lens.  Thus  I  possess  a  piece  of  ore  characterized 
by  large  crystals  of  pinkish  feldspar  (or  orthoclase)  and  a  little 
silvery  mica  (muscovite)  held  together  apparently  in  a  cavern- 
ous mass  of  quartz,  through  which  bright  specks  of  calaverite 
are  scattered.  The  quartz  contains  spots  of  green,  earthy 
chlorite  and  a  very  few  minute  cubes  of  fluorite.  White  quartz, 
as  a  distinct  veinstone,  does  not  characterize  these  lodes  to  the 
extent  usually  observable  in  gold-lodes  elsewhere,  although 
secondary  quartz  is  everywhere  found  penetrating  the  altered 
veinstone.  Pyrite  is  also  a  constant  companion  of  the  gold- 
bearing  tellurides,  and  fluorite  is  readily  to  be  seen  save  where, 
near  the  surface,  it  has  been  decomposed.  The  occurrence  of  flu- 
orite has  suggested  many  theories,  but  the  fact  that  it  forms  an 
original  constituent  of  the  granite  of  the  Pike's  Peak  region 
and  the  prevalence,  in  the  same  neighborhood,  of  such  fluorine- 
bearing  minerals  as  cryolite  and  topaz,*  renders  it  dangerous  to 
draw  inferences  connecting  it  with  the  ore-forming  agencies. 
There  is  the  appearance  of  probability  about  the  idea  that  the 
secondary  fluorite  of  the  lodes  was  derived  by  the  circulating 
waters  from  the  granite  of  a  lower  horizon,  and  it  may  be  men- 
tioned that  Fouque  showed  that  hydrofluoric  acid  in  a  liquid 
state  has  a  notable  effect  on  silica  and  silicates  by  first  de- 
composing the  uncrystallized  silicates,  or  glasses,  and  then  act- 
ing similarly  on  feldspars  and  other  acid  silicates,  then  on 
quartz,  and  lastly  upon  the  basic  silicates.  Whether  hydroflu- 
oric vapor  acts  similarly  is  an  open  question.  Under  such  cir- 
cumstances, quartz  might  be  attacked  before  feldspar. 

F.  VEINS  IN  ANDESITE  AND  ANDESITE  BRECCIA. 

The  andesite  of  Cripple  Creek  is  usually  an  augite-mica- 
andesite.  It  is  distinguished  by  having  apatite  as  one  of  its 
constituent  minerals.  Although  this  andesite  forms  the  prin- 
cipal element  of  the  breccia,  the  latter  is  notably  irregular  in- 
its  composition.  Phonolite  is  sometimes  locally  predominant, 
and  near  the  edge  of  the  volcanic  area  the  breccia  contains  a 
large  proportion  of  fragments  of  granite.  The  breccia,  since 


*  Florissant  and  the  Pike's  Peak  region  generally  are  celebrated  for  specimens 
of  topaz.  W.  S.  Stratton,  the  discoverer  and  former  owner  of  the  Independence 
mine,  was  prospecting  for  cryolite,  as  a  source  of  aluminum,  just  previous  to  his 
first  trip  to  Cripple  Creek. 


14  THE    LODES    OF    CRIPPLE    CREEK. 

it  was  laid  down  as  a  product  of  violently  explosive  volcanic 
eruption,  has  become  decomposed  and  cemented.  According 
to  Whitman  Cross,  the  decomposition  has  led  to  the  "  total  de- 
struction of  the  dark  silicates,"  such  as  the  augite,  hornblende 
and  biotite  present  in  the  original  fragments,  and  in  the  re- 
moval, by  leaching,  of  the  compounds  resulting  from  this  de- 
composition.* The  result  has  been  to  change  the  breccia  from 
dark  crumbling  material  into  a  bleached  compact  mass  which, 
in  process  of  time,  by  reason  of  pressure  and  waters  contain- 
ing kaolin,  silica  and  other  cementing  substances,  has  become 
consolidated  into  a  hard,  massive  rock.  In  the  vicinity  of  the 
lodes  the  effects  of  siliceous  solutions  are  rendered  apparent 
by  the  impregnation  of  quartz  to  such  a  degree  as  to  obscure 
the  original  fragmentary  nature  of  the  rock  and  make  the 
finer-grained  breccia,  or  tuft',  resemble  phonolite  in  texture 
and  appearance.  The  variations  in  the  andesite  and  andesite- 
breccia  are  responsible  for  corresponding  changes  of  lode- 
structure,  as  will  be  presently  illustrated. 

Fig.  6  is  a  photograph  of  the  Anaconda  lode,  as  seen  in  an 
open-cut,  in  July,  1897.  The  lode  at  this  place  forms  a  part  of 
an  andesite  dike  traversing  the  breccia.  The  dike  exhibits  a 
multiplication  of  fractures  parallel  to  its  walls,  and  along  these 
lines  of  cleavage  there  occur  seams  of  quartz  and  fluorite  car- 
rying tellurides.f  In  the  surf  ace- workings,  the  gold  liberated 
from  the  tellurides  occurred  pseudomorphic  after  sylvanite, 
distributed  in  yellow  patches  amid  purple  fluorite,  affording 
specimens  of  great  beauty .J 

When,  as  rarely  happens  at  Cripple  Creek,  the  lode  consists 
of  massive  ore  notably  separated  from  its  encasing  rock,  it  will 
be  found  that  such  definition  of  structure  is  due  to  the  presence 
of  fluorite  and  secondary  quartz  which  have  so  filled  up  the 
interstices  of  the  decomposed  breccia  as  quite  to  obscure  its 
original  character.  Fig.  7  represents  the  main  lode  of  the 
Gold  King  mine,  in  Poverty  Gulch.  At  the  time  the  drawing 

*  "Geology  and  Mining  Industries  of  the  Cripple  Creek  District,  Colorado," 
U.  S.  Geol.  Survey,  page  52. 

f  The  general  characteristics  of  the  ores  of  this  district  have  been  separately 
described.  "  The  Telluride  Ores  of  Cripple  Creek  and  Kalgoorlie,"  by  T.  A. 
Rickard,  Trans.,  xxx.,  708-718. 

t  See  "  Further  Notes  on  Cripple  Creek  Ores,"  by  Eichard  Pearce,  Proc.  Colo. 
Scientific  Society,  vol.  v.,  pp.  15-18. 


THE    LODES    OF    CRIPPLE    CREEK. 
FiG.  7 


15 


•^'••^ 

v        -     :  •  <     *  - 


. 

-'' 


BRECCIA 


16  THE    LODES    OF    CRIPPLE    CREEK. 

was  made  the  stopes  had  a  maximum  width  of  12  to  18  ft. 
The  rock,  owing  to  partial  oxidation,  seemed,  at  first  glance,  to 
be  structureless  and  homogeneous,  but  on  closer  investigation, 
prompted  by  contradictory  assays,  it  was  found  that  in  the 
middle  of  the  section  afforded  by  the  stopes,  which  were  (for- 
tunately for  the  purpose  of  observation)  unencumbered  with 
timbering,  there  was  to  be  seen  a  compact  dark  band,  A  B- 
O  D,  from  which  small  seams,  E  E,  went  out,  almost  at  right 
angles,  into  the  surrounding  breccia.  This  band,  which  was 
the  vein  proper,  also  consisted  of  breccia,  but  so  impregnated 
with  purple  fluorite  and  so  interpenetrated  by  secondary  quartz 
as  to  hide  the  fact.  Throughout  the  massive  vein-stuff  fine 
iron  pyrite  was  scattered,  and  with  the  pyrite  were  crystals  of 
calaverite,  rendering  it  very  rich.  At  intervals,  small  cavities 
lined  with  crystalline  quartz  occurred,  as  is  indicated  at  H,  H, 
in  Fig.  7.  In  these  cavities  occurred  crystals  of  native  gold 
pseudomorphic  after  calaverite.  Owing  to  their  dull,  rusty 
exterior,  they  looked  like  bits  of  rotten  wood,  and  it  required 
close  observation,  especially  underground,  to  detect  them. 
When  scratched,  they  gave  instant  testimony  of  their  precious 
nature.  Minute  stringers  of  ore,  rendered  noticeable  by  the 
color  of  the  fiuorite,  followed  the  cross-fractures  or  joints  in  the 
surrounding  breccia,  and,  as  delicate  threads,  accompanied  the 
central  vein,  A  B-C  D,  the  boundaries  of  which  were  further 
marked  by  a  granular  selvage  along  A  C. 

Fig.  8  is  very  characteristic  of  Cripple  Creek  veins  in  brec- 
cia. It  represents  the  breast  of  a  level  following  one  of  the 
branches  of  the  Bobtail  lode,  in  the  Independence  mine,  on 
Battle  mountain.  The  Bobtail  lode  itself  is  similar,  but  its 
true  structure  is  less  evident  on  account  of  a  more  diffused  im- 
pregnation of  ore.  The  oxidation  of  the  pyrite  accompanying 
gold-bearing  tell u rides  marks  the  course  of  the  ore-streaks, 
A  B  and  C  D.  They  look,  at  a  distance,  like  mere  stains ;  but 
closer  observation  discloses  the.  fact  that  they  are  partings 
along  the  lines  of  fracture  in  the  breccia,  each  of  which  forms 
the  center  of  a  narrow  band  of  oxidized  pyrite  and  very  minute, 
bright  specks  of  calaverite.  The  latter  is  seen,  under  the  mag- 
nifying glass,  to  be  in  process  of  decomposition,  the  oxidation 
of  the  tellurium  of  the  telluride  in  the  presence  of  decompos- 
ing pyrite  having  resulted  in  the  formation  of  the  tellurite  of 


THE    LODES    OF    CRIPPLE    CREEK. 


IMPREGNATION   ALONG  PARALLEL. FRACTURES 

iron*  and  the  liberation  of  the  gold  in  a  brown  amorphous 
condition,  resembling  yellow  paint  which  has  become  tarnished. 

*  This  alteration  product  has  a  definite  chemical  composition,  as  has  been  de- 
termined by  F.  C.  Knight.  See  "A  Suspected  New  Mineral  from  Cripple 
Creek,"  Proceedings  of  the  Colorado  Scientific  Society,  vol.  v. ,  pp.  66-7.1,  October  1, 
1894.  Mr.  Knight's  analysis  gave  a  percentage  of  Fe.,0,,  32.72;  TeO.,,  65.45 ;  and 
H2O,  1.83.  The  physical  characteristics  ascertained  were,  a  light-brown  color, 
a  dull  luster,  a  brilliant  and  uneven  fracture,  a  hardness  between  3  and  4,  and  a 
bright  yellow  streak. 


18  THE    LODES    OF    CRIPPLE    CREEK. 

The  tributary  streaks,  along  the  cross-joints  of  the  breccia,  are 
also  gold-bearing  for  a  short  distance  away  from  A  B  and  C  D. 

Such  parallel  partings  as  have  been  shown  in  Fig.  8  are 
sometimes  so  multiplied  as  to  become  zones  of  sheeting.  An 
example  is  exhibited  in  Fig.  9,  which  represents  a  lode  in  the 
Moon- Anchor  mine.  This  type  of  ore-occurrence  is  thoroughly 
characteristic  of  the  mines'  in  that  part  of  the  district  known  as 
Gold  Hill.  The  breccia  is  fine-grained.  The  partings  are 
about  a  quarter  of  an  inch  apart.  They  are  followed  by  minute 
seams  of  red,  gritty,  clay  in  which  the  tellurides  can  be  distin- 
guished. The  individual  seams  are  united  by  transverse  im- 
pregnations which  collectively  make  a  pocket  or  small  body  of 
ore,  in  which  it  is  not  unusual  to  encounter  patches  consisting 
of  an  almost  solid  aggregate  of  crystalline  calaverite  and  kren- 
nerite.*  This  sheeted  structure  dies  out  into  the  enclosing 
country-rock  by  the  process  of  a  gradual  widening  of  the  space 
intervening  between  each  successive  parting. 

Fig.  10  represents  the  Emerson  vein  at  the  fourth  level  of 
the  Independence  mine.  Here,  also,  the  country  is  andesite- 
breccia.  A  central  thread,  B  E,  of  fluorite  and  quartz,  is  fol- 
lowed by  a  band,  A  C,  D  F,  about  3  ft.  in  width,  of  decomposed 
rock,  which  is  gold-bearing,  and  therefore  regarded  as  a  lode. 
This  lode  appears  as  a  band  of  bleached  rock  amid  the  dark- 
gray  breccia.  It  is  marked  by  thin  veinlets  of  quartz,  and  is 
sparingly  honeycombed  with  small,  spongy  cavities,  containing 
iron  pyrite  and  fluorite.  The  ore  has  no  defined  boundaries, 
but  in  the  space  from  A  to  C  and  D  to  F  it  averages  2J  oz.  of 
gold  per  ton. 

The  breccia  and  tuff  exhibit  the  effects  of  the  thermal  waters 
which  have  penetrated  them  during  the  quiescent  stage  of  the 
volcano.  Kaolinization  of  the  feldspars  was  the  most  evident 
result;  the  dark  silicates  also  are  entirely  gone,  and  are  re- 
placed by  white  mica.f  During  the  subsequent  period,  when 
the  ore-deposits  were  in  process  of  formation,  these  decomposed 
fragmentary  rocks,  already  partially  cemented  by  their  kaolini- 
zation,  became  further  consolidated  by  siliceous  solutions,  so  as 

*  Krehnerite  is  a  telluride  of  gold,  approximating  calaverite  as  regards  compo- 
sition, but  differing  from  the  latter  in  possessing  a  perfect  cleavage.  It  was  named 
after  Professor  J.  A.  Krenner,  of  Buda-Pesth. 

t  As  observed  both  by  Lindgren  and  by  Cross. 


THE    LODES    OF    CRIPPLE    CREEK. 


19 


to  be  changed  into  a  compact  hard  rock.     Underground,  near 
the  veins,  by  reason  of  the  bleaching,  due  to  decomposition,  the 

FIG.  9 


ORE     STREAKS 


ORE   ALONG   SHEETED  ZONE 

breccia  has  the  mottled  look  which  the  miners  recognize  by  the 
term x  "porphyry."  As  in  the  case  of  the  granite,  secondary 
minerals  are  readily  found  wherever  the  breccia  has  been 


20  THE    LODES    OF    CRIPPLE    CREEK. 

changed  into  ore  and  the  groundmass  of  the  rock  is  seen  to 
have  undergone  substitution  by  fluorite  and  pyrite.  The 
former  enters  into  the  groundmass  so  thoroughly,  sometimes, 
as  to  make  it  a  purple  rock  spotted  with  bits  of  bleached  ande- 
site.  It  is  a  feature  of  the  breccia  that  the  ground-mass  of  it 
has  undergone  mineralization  more  extensively  than  the  rock- 
fragments  which  it  contains, — an  observation  which  illustrates 
the  selective  action  of  the  circulating  waters.  As  a  conse- 
quence, even  when  it  is  changed  into  ore,  the  included  pieces 
of  andesite  are  conspicuous,  and  are  often  edged  with  the  ore- 
forming  minerals,  such  as  pyrite,  fluorite  and  the  tellurides. 
However,  the  most  important  change  which  the  breccia  has 
undergone,  in  the  vicinity  of  the  lode-fractures,  is  its  silicifica- 
tion  by  impregnation  with  quartz.  This  is  not  so  apparent  as 
would  be  imagined,  because  it  does  not  occur  in  the  form  of 
bands  of  white  quartz  or  dark  hornstone,  but  rather  as  an  ill- 
defined  width  following  the  dominant  lines  of  fracture.  For  this 
reason  the  ore  is  often  harder  than  the  country-rock,  and  the 
workings  on  the  lode  require  less  timbering  than  the  cross-cuts. 

G.  VEINS  IN  PHONOLITE. 

Phonolite  is  in  many  respects  the  most  characteristic  rock 
of  the  gold-field  because  of  the  comparative  rarity,  elsewhere,, 
of  this  species  of  eruptive,  and  its  marked  association  with  the 
occurrence  of  ore  in  this  particular  mining  district.  The  essen- 
tial constituents  of  phonolite  are  nepheline  and  that  glassy 
variety  of  feldspar  termed  sanidine.  Sodalite,  noseaii,  and  a 
variety  of  augite  called  aegirine,  are  common  to  the  Cripple 
Creek  phonolite,  which,  typically,  appears  as  a  dull  greenish- 
gray,  dense,  very  hard  rock,  distinguished  from  the  other  erup- 
tives  in  the  district  by  a  schistose  structure*  that  gives  it  a 
sherd-like  fracture.  In  the  vicinity  of  the  lodes  the  greenish 
tint  (due  to  augite  and  allied  minerals)  has  been  obliterated  by 
bleaching,  and  a  speckled  or  porphyritic  appearance  is  given 
by  white  spots  of  decomposed  nosean.f 

*  Due,  according  to  Whitman  Cross,  to  the  fluidal  arrangement  of  the  tabular 
feldspars.  Op.  cit,  p.  33. 

f  This  is  especially  a  characteristic  of  the  so-called  Independence  dike,  as  seen 
at  the  third  and  fourth  levels  of  that  mine.  Professor  Judd,  F.R.S.,  from  speci 
mens  which  I  sent  to  him,  labelled  this  rock  distinctively  a  "nosean  phonolite." 
For  further  discussion  of  the  varieties  of  phonolite  occurring  in  the  region,  the 
reader  must  refer  to  Dr.  Whitman  Cross's  interesting  descriptions  in  the  "Geol- 
ogy and  Mining  Industries  of  the  Cripple  Creek  District,  Colorado,"  pp.  34  to  41. 


THE    LODES    OF    CRIPPLE    CREEK. 


21 


Phone-lite  is  normally  a  fine-grained  close-textured  rock,  and 
for  this  reason  the  alteration  which  it  has  undergone,  wherever 
it  has  been  in  the  passage-way  of  the  ore-depositing  agencies, 


FIG.  10 


B 


Sill' 


IMPREGNATION    F0LLCW//VG-  4    SING-LE 


is  rendered  more  striking.  The  Independence  dike,  which  ac- 
companies a  very  rich  vein,  has  been  so  corroded  by  the  solu- 
tions as  to  be  a  spongy-looking  porphyritic  rock,  especially 


22  THE    LODES    OF    CRIPPLE    CREEK. 

wherever  it  happens  to  have  lain  in  the  path  of  the  ore-bearing 
solutions  which  found  a  way  along  the  vein-fracture.  Where  nor 
thus  altered  by  impregnation,  the  phonolite  is  often  so  cleaved 
by  cracks  parallel  to  its  walls,  and  to  those  of  the  accompany- 
ing lode,  as  to  resemble  a  shale.  At  such  places  it  is  usually 
mineralized  by  the  occurrence  of  pyrite  and  tellurides  along 
the  faces  of  the  cracks. 

The  phonolite  occurs  not  only  within  the  central  mass  of 
breccia,  but  also  outside  the  immediate  boundaries  of  the  vol- 
canic area,  penetrating  the  granite  in  dikes  and  in  large,  irreg- 
ular, intrusive  masses,  one  of  which  forms  Mt.  Pisgah,  so  cele- 
brated in.  connection  with  the  early  history  of  the  Pike's  Peak 
region.* 

In  the  distribution  of  ore,  phonolite  plays  an  important  part, 
as  the  sequel  will  show.  It  has  already  appeared  in  Fig.  4,  but 
not  in  so  direct  a  relation  as,  for  instance,  in  Figs.  5  and  11, 
now  to  be  described. 

Fig.  11  is  especially  interesting  when  taken  in  connection 
with  Figs.  3,  4  and  5,  because  it  represents  the  same  vein  amid 
a  different  geological  environment.  The  dike  in  Fig.  4  is  the 
same  as  the  one,  B  C-E  F,  in  this  drawing,  while  the  body  of 
phonolite  to  the  left  is  a  tongue  from  a  large  mass  of  brecciated 
phonolite  occurring  in  this  part  of  the  mine.  The  feature  to 
which  it  is  desired  to  draw  attention  is  the  distribution  of  ore 
at  this  point.  The  dike,  B  C-E  F,  is  the  traversing  breccia. 
The  main  ore-streak  consists  of  the  width  of  breccia,  26  inches 
across,  separating  the  phonolite  at  B  E  from  that  at  A  D.  There 
is  some  ore  also  in  the  phonolite  dike,  especially  along  C  F, 
where  it  is  so  shattered  as  to  resemble  a  shale.  Threads  of  ore 
also  occur  along  the  other  cleavage-planes  in  the  phonolite, 
and  are  (observe  G  G)  widely  distributed  through  the  breccia 
to  the  east,  so  as  to  form  a  large  mass  of  comparatively  low- 
grade  ore.  By  way  of  summary,  it  may  be  said  that  the  ore  is 
scattered  through  the  breccia  and  is  concentrated  near  the 
edge  of  the  phonolite,  occurring  in  the  body  of  the  latter  only 
where  it  happens  to  be  shattered. 

In  Fig.  5  the  Independence  vein  is  again  illustrated,  as   it 

*  The  Mt.  Pisgah  story  is  told  in  my  earlier  paper,  "The  Cripple  Creek  Gold- 
field."  Proceedings  of  the  Institution  of  Mining  and  Metallurgy,  London.  Vol. 
viii.,  pp.  50-51. 


THE    LODES    OF    CRIPPLE    CREEK. 


23 


appeared  in  the  raise  between  the  800-ft.  and  the  700-ft.  levels, 
in  June,  1899.     The  same  dike  of  phonolite,  E  F-G  H,  having 


.P. 


BRECCIA 


-PHONOLITE: 


here  a  width  of  from  18  to  20  inches,  occupies  the  center  of  the 
band  of  gold-bearing  granite,  A  C-B  D,  which  is  the  lode. 


24  THE    LODES    OF    CRIPPLE    CREEK. 

When  sampling  the  ore,  previous  to  shipment,  it  was  found 
that  the  dike  only  yielded  fines  or  "  screenings,"  indicating  that 
the  fine  particles,  which  came  oft'  the  cleavage-planes,  carried 
whatever  gold  there  was  in  the  phonolite.  In  the  case  of  the 
granite,  on  the  contrary,  the  bulk-ore  was  the  best.  The  lode 
extends  from  A  to  C ;  the  left-hand  portion  is  about  2  ft.  wide, 
it  is  traversed  by  streaks  of  fluorite,  and  is  richest  along  the 
contact  with  the  dike.  This  is  also  true  of  the  right-hand  por- 
tion, which  is  2J  ft.  wide  and  similar  in  character.  The  richest 
parts  follow  the  dark  streaks  composed  of  purple  fluorite  asso- 
ciated with  iron  pyrite,  accompanied  by  the  tellurides,  sylvan- 
ite  and  calaverite.*  The  walls,  A  A  and  B  B,  are  clean  and 
defined,  with  a  slight  selvage.  The  outer  rock  is  a  fresh  pink 
granite,  the  inner  lode-granite  being  kaolinized  and  otherwise 
altered. 

Fig.  12  was  obtained  at  the  fourth  level  of  the  Independence 
mine,  at  a  place  where  a  part  of  the  Bobtail  vein,  in  its  north- 
ward course,  penetrates  a  mass  of  phonolite,  which,  apparently, 
is  only  a  local  enlargement  of  another  dike  crossing  the  breccia 
at  a  slight  angle  with  the  vein.  The  main  streak  of  ore,  even 
at  this  point,  is  in  breccia,  so  that  it  is  only  the  enlargement  of 
the  Bobtail  lode,  5  to  6  ft.  wide,  which  is  considered  to  reach 
into  the  phonolite.  The  planes  of  fracture  are  well-marked. 
Where  the  ore  occurs,  the  rock  is  sheeted  along  lines  which 
are  parallel  to  the  lode,  and  accompanying  these  fractures  there 
are  found  small  threads  of  extremely  rich  material.  That 
marked  A  A  is  the  largest ;  it  is  only  from  a  quarter  to  half 
an  inch  thick,  and  consists  of  little  crystals  of  iron  pyrite, 
which,  by  reason  of  their  partial  oxidation,  give  the  ore-streak 
a  dull-red  color,  and  render  very  distinct  its  passage  through 
the  light-gray  rock.  Tellurides  accompany  the  pyrite,  and  are 
the  cause  of  the  high  gold-contents  of  the  ore.  The  other 
streaks  are  similar,  though  smaller.  The  surrounding  phono- 
lite  is  peppered  over  with  minute  cubes  of  purple  fluorite, 
which  darken  it.  t  Many  of  the  planes  of  fracture  are  lined 
with  the  same  material.  The  whole  mass,  from  A  A,  and 
across  C  C,  for  a  width  of  6  ft.,  assayed  3  to  4  ounces  of  gold 
per  ton. 

*  And  especially  a  massive  granular  telluride,  found,  by  Mr.  W.  E.  Ford,  to 
be  a  variety  which,  as  regards  composition,  is  intermediate  between  calaverite  and 
sylvanite. 


THE    LODES    OF    CRIPPLE    CREEK. 


25 


H.  VEINS  IN  BASALT,  TRACHYTIC  PHONOLITE,  ETC. 

Numerous  dikes  of  nepheline  basalt,  the  last  product  of  the 
Cripple  Creek  volcano,  occur  in  the  district,  especially  in  its 
southwestern  portion.  The  Raven,  Elkton,  Anna  Lee,  Black 

PIG.  12 


RICH       -STKEAKS      \  M 


Diamond,  Moose,  Bertha,  Trail  and  other  mines  contain  lodes 
which  are  an  integral  portion  of  such  dikes.  They  are  usually 
much  decomposed,  hy  reason  of  their  basic  constitution,  and 
do  not  make  any  showing  at  the  surface.  Of  the  several  lodes 
associated  with  these  basalt  dikes,  the  Elkton  is  the  most  inter- 


26  THE    LODES    OF    CRIPPLE    CREEK. 

eating.  A  characteristic  section  is  given  in  Fig.  13,  which 
illustrates  this  lode  as  seen  in  the  stopes  above  the  fifth  level, 
in  May,  1899.  The  dike  is  nearly  4  ft.  wide,  from  A  C  to 
B  D,  and  traverses  the  andesitic  breccia  of  Raven  Hill.  It 
shows  a  distinct  lamination  parallel  to  the  walls.  This  is  very 
strong  along  the  outer  edges  of  the  basalt,  where  it  is  also 
bleached  and  decomposed.  The  central  portion  of  the  dike 
appears  as  a  hard,  dark-gray  mottled  rock,  marked  by  evident 
cross-jointing.  The  dike  is  nearly  vertical,  inclining  slightly 
to  the  east.  The  cross-joints  dip  northward  at  an  angle  of 
about  20°,  and  facilitate  stoping.  The  basalt  exhibits  the 
effects  of  mechanical  stress  by  its  lamination,  which  is  suffi- 
ciently pronounced  in  places  to  give  the. rock  the  character  of 
shale  and  to  render  mining  dangerous. 

Evidences  of  chemical  alteration  are  apparent,  and  they  co- 
incide with  the  occurrence  of  ore.  The  latter  usually  follows 
the  west  wall,  but  occasionally  it  is  found  on  both  walls,  and 
more  rarely  in  a  scattering  through  the  mass  of  the  dike. 
The  total  width  of  ore  in  these  particular  stopes  averaged 
about  18  inches. 

A  remarkable  feature  of  the  section  is  the  inclusion,  within 
the  dike,  of  fragments  of  granite.  The  largest  of  these  (at  Q)  is 
4  inches  wide.  In  the  neighboring  stopes  such  inclusions  were 
frequently  seen.  This  suggests  the  vicinity  of  the  basal  granite. 
In  fact,  the  level  above  which  this  drawing  was  made  leaves 
the  breccia  and  enters  the  outer  granite  at  a  point  only  850  ft. 
from  the  place  here  illustrated.  At  an  intermediate  point, 
where  the  Elkton  dike  is  not  ore-bearing,  I  secured  the  section 
shown  in  Fig.  15 ;  here  larger  fragments  of  granite  are  in- 
cluded within  the  basalt,  and  the  breccia  itself  is  seen  to  con- 
tain numerous  fragments  of  the  older  rock. 

In  Fig.  13,  which  is  a  characteristic  section  of  the  lode,  the 
main  streak  of  ore  is  seen  to  follow  the  western  boundary  of 
the  dike,  and  to  include  the  rock  on  either  side  of  that  line,  so 
as  to  obscure  it.  There  is  no  parting  or  selvage  to  mark  the 
line  of  division  between  the  basalt  and  the  breccia ;  that  is,  it 
is,  as  a  miner  would  express  it,  "  a  frozen  contact."  The  ore 
spreads  across  into  both.  Both  alike  exhibit  the  destruction  of 
their  original  soluble  constituents  and  the  replacement  by 
veinstone,  especially  fluorite.  The  breccia  is  bleached  by  the 


THE    LODES    OF    CRIPPLE    CREEK. 


27 


kaolinization  of  the  feldspar,  and  is  honeycombed  with  cavi- 
ties which  contain  water-quartz  in  various  forms,  especially 
hyalite.  The  telluricles,  sylvanite  and  calaverite,  are  scattered 
through  this  decomposed  hreccia  and  extend  into  the  adjoin- 


S''1-—     '  ^.:-1' 


;- 

%f?$.£~yiW$-*Z& ^^ .'  r?;**X*.?*?::.;  £\*$i 

;  *v.  p^pfe^::?  ^^if^sS^I 

,-  *    «!.««.    \    v"       .-      *•  ».•->•-  17,          -v-*     -«i«^.^       . •>'<>• '--. -?;V_.-__J>- 

:-^^^~?^ ;  C j"^- - ^x^H-r.;.^ -. °-'?s 


D 


'^^^^^^  s 

%'-  <« v< vrv^^«*<r-<  v  r^^M***  i  r<"/      > 

'ai^iiS&sa;        IM 


^v.^   /D 


ing  basalt.  This  latter  is  also  bleached  to  a  dull  gray,  and  is 
seamed  with  ore  along  the  faces  of  the  cleavages.  Although 
neither  the  walls  of  the  dike  nor  the  ore-streaks  themselves  are 
indicated  by  selvages,  it  is  noteworthy  that  several  very  dis- 
tinct partings,  followed  by  clay-seams,  traverse  the  basalt  in 


28 


THE    LODES    OF    CRIPPLE    CREEK. 


lines  parallel  to  its   strike.     They  are   shown  at  G  M,  H  BT, 
K  O  and  L.  P. 

This  section  presents  another  interesting  feature.  It  will  be 
noticed  that  on  the  east  side  the  breccia  is  brecciated ;  that  is, 
the  fragmentary  rock  has  been  broken  again  into  fragments  by 
a  later  movement  which  took  place  along  the  course  of  the 
dike.  It  is  likely  that  the  other  side  was  similarly  affected,  but 

FIG.  15 


ELKTON    DIKE 

I  could  not  determine  the  fact  with  certainty,  owing  to  the  de- 
composition of  the  rock  and  the  deposition  of  ore.  That  this 
movement  bears  some  relation  to  the  period  of  ore-formation 
is  most  likely ;  that  it  occurred  subsequent  to  the  complete 
consolidation  of  the  dike  is  rendered  certain  by  another  sec- 
tion, shown  in  Fig.  16,  obtained  in  a  neighboring  level  of  the 
same  mine.  Here  a  lateral  offshoot,  A  B,  of  basalt  is  seen  to 


THE    LODES    OF    CRIPPLE    CREEK. 


29 


be  clearly  broken  by  vertical  movement.  The  central  portion 
of  the  dike  is  dark  green,  with  secondary  chlorite,  and  is 
speckled  by  feldspar  phenocrysts.  The  dike,  C  D— E  F,  only  11 
inches  wide  at  this  point,  also  exhibits  a  banded  structure  along 
the  sides,  suggesting  a  differentiation  between  the  core  and  its 

FK;.   16 


a:,. 


ANDESITE 

ELKTON    DIKE 


GR/\NtT£ 


^dges,  due  to  a  less  complete  crystalline  development,  conse- 
quent upon  rapid  cooling  at  the  time  of  intrusion  into  the 
breccia.  The  latter  is  seen  to  contain  numerous  fragments  of 
granite,  for  this  section,  also,  was  secured  at  a  distance  of  500 
feet  only  from  the  granite  rim. 


30 


THE    LODES    OF    CRIPPLE    CREEK. 


iiiM 


il 

#;vVi::;#- 


i£;£SS(* 

^•^Kfe-vv 


K^^&SiS} 

&&;&••?:&§ 

g*?|l%l 

Ilil 


Another  section  is  illus- 
trated in  Fig.  14,  obtained  in 
the  same  stopes  as  Fig.  13, 
but  about  50  ft.  farther  north. 
The  dike,  A  C-F  E,  is  3  ft. 
10  inches  wide.  It  has  a  very 
distinctly  laminated  structure, 
and  in  places  it  breaks  like 
shale..  It  is  spotted  with  vesic- 
ular cavities  which  are  lined 
with  zeolites  and  hydrous 
quartz.  The  ore  occurs  along 
each  wall  of  the  basalt,  spread- 
ing over  into  the  encasing 
breccia.  No  selvage  divides 
the  dike  from  the  outer  rock, 
but  the  bands  of  decom- 
posed ore-bearing  basalt,  A 
B-C  D,  and  L  F-M  E,  are 
separated  from  the  central 
mass  of  the  dike  by  distinct 
clay-partings,  B  D  and  L  M. 
The  ore-bearing  edges  of  the 
dike  are  rich  in  tellurides. 
That  part  of  the  ore-streak 
which  consists  of  mineralized 
breccia,  F  H-E  G,  appears  as 
a  kaolinized  rock  darkened 
by  spots  and  streaks  of  purple 
fluorite.  It  is  from  2  to  6 
inches  wide,  and  is  fairly  well 
distinguished  from  the  outer 
gray  breccia  by  the  contrast  of 
color.  The  enclosing  rock  is  a 
fairly  coarse  breccia,  marked 
by  sintery  spots,  due  to  altera- 
tion. These  are  frequently 
ore-bearing,  by  reason  of  tel- 
lurides. The  slips  or  parallel 
fractures,  S  S,  also  carry  a 
little  ore  upon  their  faces,  and 


THE    LODES    OF    CRIPPLE    CREEK.  31 

permit  the  rock  to  be  mined  at  a  profit,  because  it  yields 
"  screenings  "  or  fines,  which  are  rich  enough  to  be  sent  to  the 
smelter. 

In  Fig.  17  there  is  given  a  characterization  of  the  chief  fea- 
tures of  the  Elkton  lode-structure.  The  vein  is  remarkably 
straight ;  in  the  breccia  it  appears  as  one  or  more  small  frac- 
tures carrying  tellurides,  accompanied  by  chlorite ;  when  the 
vein  encounters  the  basalt  dike,  it  follows  the  latter  as  long  as 
the  basalt  maintains  a  direction  similar  to  the  strike  of  the 
vein ;  when  the  basalt  is  crossed  by  a  later  dike  of  phonolite, 
the  vein-fractures  persist  across  the  phonolite,  and  spread  so  as 
to  make  a  large  width  of  gold-bearing  rock. 

The  trachytic  phonolite  of  Cripple  Creek  occurs  in  large 
intrusive  masses,  which  are  penetrated  by  later  dikes  of  phono- 
lite  and  basalt.  It  has  a  decided  porphyritic  habit  by  reason 
of  the  occurrence  of  large  orthoclase  crystals  in  a  dense  ground- 
mass.  The  workings  of  the  Legal  Tender  (or  Golden  Cycle) 
property  are  in  this  rock,  and  afford  examples  of  lode-structure. 
In  Figs.  18  and  19  the  Harrison  vein  is  illustrated  as  it  is  seen 
in  this  mine. 

The  Harrison  vein  consists  of  a  band  of  shattered  coun- 
try in  the  trachytic  phonolite ;  the  center  of  it  is  marked  by  a 
leader,  usually  very  rich,  bordered  by  fractured  rock  having  a 
very  variable  width.  This  leader  is  shown  at  B  E  in  Fig.  18 
and  A  B  in  Fig.  19. 

In  the  first  example,  secured  just  above  the  6th  level,  B  E 
appeared  underground  as  a  streak  of  crushed  rock,  3  to  4  inches 
wide,  and  dark-red  in  color  by  reason  of  the  oxidation  of  pyrite. 
The  band  of  brecciated  and  bleached  rock  on  the  hanging-wall 
side,  from  A  to  B  and  from  E  to  D,  contained  numerous  little 
threads  and  spots  of  pyrite,  accompanied  by  just  sufficient 
gold  tellurides  to  make  it  low-grade  ore.  The  corresponding 
band  on  the  foot-wall,  from  B  to  C  and  from  E  to  F,  was  less 
decomposed  and  exhibited  more  clearly  a  defined  system  of 
fractures,  the  latter  being  lined  with  fine-grained  iron  pyrite. 
In  Fig.  19,  A  B  appeared  underground  as  a  seam,  1  to  1 J 
inches  wide,  of  white,  gritty  mud,  very  rich  in  gold.  The  hang- 
ing-wall, from  A  to  C  and  from  B  to  D,  is  brecciated  and 
ore-bearing,  as  is  the  corresponding  band,  A  E-B  F,  on  the 
foot-wall ;  but  the  latter,  being  less  fractured,  is  also  less  rich 
than  the  other  side  of  the  lode. 


32 


THE    LODES    OF    CRIPPLE    CREEK. 
Fro.  18 


+  X     +    X 

-h    X     +•    X  U-     '    *  .  |  •  , 

•     ^,   '  •      I: 


X     f-     X    f-    *.''      -   T-/J1 


^-x  */  ./    .'-.-I 


t-  >.  •       •.    • 


TRACHrTE    PORPHYRY 


VEIN 

The  widest  ore  found  on   the  Harrison  vein   is   found  at 
places  where  spurs  or  subordinate  veins  joined  the  main  lode. 


THE    LODES    OF    CRIPPLE    CREEK. 
FIG.   19 


33 


X  +-    X     4-     x-t-X4-X/v 

t    X     4-     X4-X4-X  4-/*;-  . 
t-X     4-     *     4-    x.     4-   X 

X    4-    X      4-     X    4-    X  4- 
X  4-    X    4-    X,   4-  X    4-    X  \  X/, 

4*   X     "t~     '  -   T-    '->    i    "/x 
X     -f-     X    H-    X    4-   X/ 
X^X      4-X4-X/^^X/, 

4-   x    -f-   x    -I-  x  4-/.\x  /  /* 

4-  X    +-     x     4-    X    f  /  «  >0  /,  \ 

X    4-    X     1"    X    t" 


X  X-     •*-     X 

f-X-»-/X     -f-      X4-X 
X      1-  X 


.14-      X     -H      X.4-     A4-Xf- 


ORE 


H/\RKiSON    VEIN.  No.*/ 

This  gives  the  ore-bodies  a  disconnected  character,  a  series  of 
linked  enlargements,  rather  than  the  appearance  of  a  persistent 


THE    LODES    OF    CRIPPLE    CREEK. 


ore-streak;  when  the  ore-body  narrows,  the  line  of  the  lode 
becomes  indistinct,  being  indicated  merely  by  a  group  of  irreg- 
ular fractures  scarcely  different  from  the  fractures  to  be  seen  in 
the  crosscuts,  and  not  recognized  as  "  veins  "  simply  because 
they  do  not  carry  pay-ore. 


FIG.  30 


r.f^-  W 


tLzili}    PMOIX/OLITE-  y    C-OCD-BE4RING 

Vein  Traversing  a  Sheet  of  Phonolite. 

I.  VEIN  CROSSING  A  SHEET  OF  PHONOLITE. 

The  occurrence  recorded  in  Fig.  20  represents  the  Orizaba 
vein,  on  Beacon  Hill,  as  seen  in  September,  1899.  The  coun- 
try is  granite,  which,  in  this  part  of  the  district,  is  penetrated 
by  several  sheets  and  intrusive  cores  of  phonolite.  The  Orizaba 
vein  cuts  through  at  least  two  of  these  flat  intrusions,  and  in 
doing  so  presents  several  interesting  features.  Fig.  21  illus- 
trates the  relation  between  the  geological  structure  and  the 


THE    LODES    OF    CRIPPLE    CREEK. 


35 


mine-workings  at  220  ft,  below  the  surface.  The  phonolite  is 
from  9  to  11  ft.  thick,  dipping  flatly  both  northward  and  west- 
ward. At  the  south  winze  the  phonolite  is  cut  at  a  point  4£ 
ft.  down,  and  is  found  to  extend  thence  to  a  depth  of  13  J  ft. 
The  remainder  of  the  winze,  to  the  bottom,  at  23f  ft.,  is  in 
granite.  The  north  winze,  which  is  77  ft.  distant  from  the 
other,  penetrates  phonolite  at  13J  ft.,  and  strikes  granite  again 
at  the  bottom,  23  ft.  down.  The  phonolite  is  faulted  about  14 
in.,  B  to  C  and  D  to  E,  Fig.  20,  by  the  fracture  which  marks 
the  line,  A  B  D  F,  of  the  vein.  In  the  granite  the  vein  ap- 
pears as  a  narrow  seam,  but  in  its  passage  through  the  phono- 
lite  it  opens  out  and  forms  a  series  of  cavities  which  are  lined 
with  long  prismatic  crystals  of  sylvanite,  encrusted  with  quartz, 
affording  specimens  of  great  beauty,  and,  of  course,  of  extra- 
ordinary richness.  The  tellurides  also  impregnate  the  rock 
encasing  the  fracture. 

FlO.  21 
Leuel 


Granite 


phon 


olite 


Sheet 


Granite 


This  shows  the  Relation  of  the  Phonolite  Sheet  (Fig.  20)  to  the  Workings. 

In  crossing  the  phonolite,  the  lode-fracture  straightens  up ; 
in  leaving  it,  and  passing  into  the  granite  again,  it  flattens. 
While  traversing  the  9  to  10-ft.  sheet  of  phonolite,  and  for 
a  farther  distance  of  15  to  20  ft.  into  the  granite  above  the 
phonolite,  the  vein  carries  very  rich  ore,  forming  a  flat  body, 
the  pitch  of  which  conforms  to  the  dip  of  the  phonolite. 
Farther  up,  the  vein  becomes  impoverished,  until,  at  a  point  85 
ft.  above  the  220-ft.  level,  it  encounters  another  flat  sheet  of 
phonolite,  characterized  by  a  repetition  of  the  conditions  just 
described.  In  the  stopes  above  the  220-ft.  level  the  granite  is 
mined  not  only  for  the  4  or  5  inches  of  vein  proper,  but  also 
for  as  much  as  5  or  6  ft.  into  the  hanging-wall,  which  is  tra- 
versed by  telluride  threads,  parallel  to  the  line  of  the  vein.  In 
the  phonolite  the  vein  is  characterized  by  "  vughs  "  or  cavities, 
2  to  8  inches  wide,  yielding  an  average  of  about  5  inches  of  rich 


36  THE    LODES    OF    CRIPPLE    CREEK. 

ore.  This  rich  ore  does  not  continue  downward  into  the 
granite  under  the  phonolite ;  the  vein  thins  out,  becoming  a 
mere  thread  amid  a  series  of  parallel  seams,  which  give  the 
granite  a  schistose  character  for  a  width  of  one  foot. 

J.  GENERAL  OBSERVATIONS. 

The  occurrence  of  ore  in  the  Cripple  Creek  district  is  inti 
mately  related  to  the  distribution  of  fractures.  As  a  rule,  the 
veins,  in  their  strike  and  dip,  exhibit  an  evident  sympathy  with 
the  dikes,  more  particularly  those  of  phonolite,  which  are  also 
the  most  numerous.  It  is  true  that  the  locality  of  Bull  Hill  is 
crowded  with  a  very  large  number  of  veins  which  appear  to  be 
independent  of  dikes,  but  it  is  a  fact,  proved  by  the  experience 
of  mining  in  the  district,  that  these  numerous  veins  are  less 
persistent  and  carry  ore-bodies  which  are  more  uncertain  than 
those,  for  example,  of  Battle  Mt.  and  Raven  Hill,  where  the 
veins  are  obviously  connected  with  dikes.  It  is  possible  to  go 
further  and  state  that  the  explorations  carried  out  in  the  ex- 
treme eastern  and  western  parts  of  the  region,  such  as  the 
eastern  part  of  Gold  Hill  and  the  corresponding  slope  of  Big 
Bull,  both  of  which  are  still  well  within  the  volcanic  area,  have 
tended  to  prove  that  the  absence  of  dikes  means  the  want  of  a 
factor  usually  very  favorable  to  the  finding  of  ore.  Nor  is  this 
a  matter  of  surprise.  The  veins  are  obviously  the  sequel  to 
the  volcanic  activity  which  occurred  in  this  region,  and  it  is  a 
reasonable  deduction  that  the  agency  of  ore-precipitation  was 
linked  to  that  of  the  thermal  waters  which  marked  the  last 
stage  of  the  dying  volcano. 

The  principal  veins,  such  as  those  which  have  made  rich 
mines  out  of  the  territory  controlled  by  the  Independence, 
Portland,  Strong,  Gold  Coin,  Granite,  Anaconda,  Elkton,  Gold 
King  and  other  companies,  either  follow  dikes  or  have  a  course 
lying  closely  parallel  to  them.  It  is  noticeable  that  the  later 
fracture  constituting  the  vein  is  apt  to  be  straighter  than  the 
older  line  of  fracture  occupied  by  the  dike ;  so  that  the  vein 
may  be  compared  to  a  road,  alongside  a  river,  which  avoids  the 
excessive  bends  of  the  latter  and  keeps  a  course  as  straight  as 
is  consistent  with  a  given  general  direction,  namely,  that  of  the 
river.  The  Independence  main  lode  illustrates  this  observa- 
tion, as  the  accompanying  plan  will  indicate.  (See  Fig.  22.) 


THE    LODES    OF    CRIPPLE    CREEK. 


37 


This  exhibits  a  portion  of  the  first  level  where  the  vein  is 
mostly  in  the  granite.  It  will  be  seen  that  when  the  vein- 
fracture  encounters  the  phonolite  dike  it  follows  the  latter ;  or, 
looking  at  the  occurrence  from  the  opposite  standpoint,  when 


-H-    -h    -*• 


s+ 


the  phonolite  makes  a  sharp  turn  to  the  west,  the  vein  main- 
tains its  general  strike.  Near  Ko.  1  shaft  the  vein  crosses  the 
dike.  This  is  shown  in  greater  detail  in  Fig.  23,  at  E-D,  where  it 
is  evident  that  the  vein-fracture  persists  in  its  course  despite  the 


38  THE    LODES    OF    CRIPPLE    CREEK. 

fact  that  it  has  to  cross  the  sharp  bend  made  by  the  dike.  At 
the  place  of  crossing,  E  D,  there  are  one  or  two  small  stringers 
of  ore  which  serve  to  connect  the  lode  on  either  side  of  the  pho- 
nolite. Between  C  and  E  the  ore,  here  4  ft.  wide,  narrows 
down,  by  steplike  succession,  from  one  joint-plane  in  the  gran- 
ite to  the  next.  Beyond  the  ~No.  1  shaft,  as  will  be  seen  in 
Fig.  22,  the  Ipde  widens  until,  at  the  contact,  it  is  10  to  15  ft. 
across.  At  this  contact,  where  the  overlying  breccia  rests  on 
the  granite,  the  ore  is  in  decomposed  granite,  having  no  marked 
boundaries  save  where,  on  the  east,  it  lies  against  the  dike. 
Immediately  north  of  the  contact  the  vein  narrows  and  crosses 
the  phonolite  only  to  disappear.  At  lower  levels  it  has  been 
traced  much  farther  northward. 


i*" E        f**M    6R.ANITE,    /7c?l  PHONOL.IT& 

Lj!^— -J  i£_y-J 

»NO£PE'NDE  NCE.    GROSSING-     DIKE 

The  obvious  connection  between  phonolite  dikes  and  veins 
has  led  to  the  idea  that  phonolite  itself  is  notably  an  ore- 
carrier.  This  is  scarcely  true.  The  details  of  lode-structure 
described  earlier  in  this  account  indicate  that  the  gold-ore  ob- 
tained from  the  phonolite  comes  mainly  from  the  places  where 
the  ore-bodies  in  the  granite  or  in  the  breccia  are  in  immediate 
contact  with  the  dikes  ;  or,  if  ore  is  found  within  the  phonolite 
itself,  it  is  at  isolated  spots,  where  the  line  of  a  lode  crosses  a 
dike  and  makes  a  scattering  along  the  fractures  produced  by 
the  crossing.  Mistakes  in  this  connection  have  been  made  by 
confounding  phonolite  with  certain  finer-grained  breccias  and 
tuffs  which,  by  impregnation  with  quartz,  have  put  on  the  ap- 
pearance of  a  close-textured  crystalline  rock.  This  happens 


THE    LODES    OF    CRIPPLE    CREEK.  39 

frequently  in  the  mines  on  Gold  Hill.  Where  valuable  ore  is 
really  taken  from  phonolite,  it  will  be  found  that  its  true  char- 
acter is  sufficiently  indicated  by  the  fact  that  it  is  secured  in 
the  form  of  "  screenings."  The  fine,  powdery  material  ob- 
tained by  passing  the  ore  over  a  wire-screen  (which  separates 
all  the  larger  fragments,  and  concentrates  the  small  proportion 
of  rich  ore),  occurs  as  an  encrustation,  of  fluorite  and  tel- 
lurides,  which  lines  the  numerous  cracks  of  a  phonolite  dike. 
That  shattering  of  the  dense,  fine-grained  siliceous  rock  ap- 
pears to  be  an  essential  factor  in  the  deposition  of  the  ore. 
In  this  connection  it  is  a  notable  fact  that  the  phonolite 
dikes  are  found  occasionally  to  widen  into  tongues  or  cores  of 
large  dimensions,  which,  if  they  lie  on  the  strike  of  a  series  of 
veins,  are  so  much  shattered  as  to  permit  of  a  generous  dis- 
semination of  ore.  Such  an  ore-body,  of  noteworthy  size  and 
richness,  occurs  in  the  Independence  mine  at  the  second,  third 
and  fourth  levels,  pitching  northward  more  flatly  than  the  con- 
tact with  which  it  was  originally  supposed  to  coincide,  causing 
a  confusion  of  ideas  very  detrimental  to  the  development  of  the 
mine. 

The  chief  characteristic  of  the  ore-bodies  of  Cripple  Creek 
is  that  they  are  essentially  impregnations  spreading  outward 
from  lines  of  fracture ;  therefore,  it  is  not  surprising  that  the 
distribution  of  ore  is  affected  by  the  changes  in  country.  Prof. 
Penrose  has  pointed  out  that  "  the  character  of  the  fissures  of 
the  district  is  much  affected  by  the  nature  of  the  rocks  they 
intersect,"*  and  it  is  but  a  further  step  to  connect  this  observa- 
tion with  the  distribution  of  ore.  In  discussing  this  aspect  of 
the  inquiry  it  is  preferable  to  avoid  the  use  of  terms  such  as 
"  fissure,"  with  its  old  associations  of  open  crevasses  and  gaping 
cavities,  and  to  risk  the  weariness  of  iteration  by  employing 
the  word  "  fracture,"  which  goes  no  further  than  to  suggest 
dislocation  or  breaking  without  necessarily  bringing  in  the 
idea  of  an  open  space,  because  the  experience  of  mining  in  the 
Cripple  Creek  district  is  all  against  the  theory  that  open  spaces 
are  the  necessary  adjuncts  to  ore-deposition ;  and  Mr.  Becker's 
well-known  dictum,  made  in  connection  with  the  Comstock, 
that  "  the  first  condition  for  the  formation  of  a  quartz  body  is 


"  Geology  and  Mining  Industries  of  the  Cripple  Creek  District,"  U.  S.  Geol. 
Survey,  p.  143. 


40  THE    LODES    OF    CRIPPLE    CREEK. 

an  opening  to  receive  it,"*  is  daily  contradicted  by  the  under- 
ground workings  of  this  district,  as  it  has  been  by  many  others 
with  which  I  am  familiar.  The  open  spaces  which  are  fre- 
quently encountered,  especially  in  the  mines  situated  on  the 
south  slope  of  Bull  Hill  and  on  Ironclad  Hill,  are,  as  a  rule,f 
notably  unfavorable  to  the  finding  of  ore ;  and  while  certain 
veins,  among  which  the  Bobtail,  in  the  Independence  mine, 
may  be  instanced,  are  indeed  marked  by  frequent  "  vughs  "  or 
cavities,  these  cavities  do  not  contain  ore,  nor  is  their  presence 
a  factor  in  connection  with  the  distribution  of  good  ore ;  quite 
otherwise,  all  such  "  pot-holes "  are  disliked  by  the  mine- 
foremen,  because  they  coincide  with  lean  places ;  and  by  this 
is  understood  not  only  poverty  in  respect  of  gold-bearing  min- 
erals, but  also  an  absence  of  gangue,  such  as  quartz,  fluorite, 
and  the  other  constituents  of  the  ores  of  the  region.  This  all 
goes  to  show  that  the  term  "  fissure "  and  the  associations 
which  go  with  it  are  to  be  avoided  in  an  attempt  to  convey  the 
real  nature  of  the  lode-structure,  because  it  cannot  be  empha- 
sized too  much  that  the  ores  of  the  district  occur  as  a  disper- 
sion into  the  rock  where  it  is  traversed  by  lines  of  fracture,  not 
only  in  the  fracture  itself,  which  is  often  only  a  mere  parting, 
but  also  along  the  minor  cracks  and  porosities  of  the  enclosing 
rock.  * 

The  physical  and  chemical  characters  of  the  rock — the  first 
more  than  the  second — are,  consequently,  a  primary  factor  in 
determining  the  shape  and  extent  of  the  impregnation  which 
constitutes  the  lode.  Close-grained  rocks  are  apt  to  be  more 
fissile  and  less  porous ;  coarse-textured  rocks  are  likely  to  break 
in  a  larger,  more  irregular  manner,  but  they  are  often  more 
penetrable  by  solutions.  The  phonolite  and  the  breccia  exhibit 
extreme  divergence  in  this  respect.  Granite  resembles  the 
breccia  because  it  is  coarsely  granular,  but  its  jointings  are 
more  regular;  basalt  resembles  the  phonolite  in  texture,  but, 

*  Quoted  from  the  Comstock  monograph. 

f  An  interesting  exception  was  recently  encountered  on  the  seventh  level  of 
the  Elkton  mine,  where  a  cavity,  having  maximum  dimensions  of  20  x  20  x  35 
ft. ,  was  found  to  contain  ore  and  water.  The  latter  was  struck  in  such  quantities 
as  seriously  to  impede  operations  ;  the  ore  occurred  in  a  mass  of  brecciated  rock, 
lining  the  fractures  and  penetrating  the  shattered  country,  especially  near  the 
periphery  of  the  mass.  It  looked  like  a  thermal  spring  which  had  become 
choked  before  reaching  the  surface. 


THE    LODES    OF    CRIPPLE  'CREEK.  41 

on  account  of  its  basic  composition,  the  weak  places  in  it  are 
more  readily  searched  out  by  corroding  waters. 

This  "  structural  dependency  "  (as  it  may  be  termed)  of  the 
lodes  in  relation  to  the  rock  is  manifested  not  only  by  the  char- 
acter of  the  vein-fractures  but  also  in  the  manner  of  their  im- 
pregnation by  ore.  Thus,  while  the  bands  of  ore  in  granite 
are  often  wanting  in  walls,  yet  on  the  whole  they  are  less  lack- 
ing in  definition  than  the  breccia,  because  structural  lines  in 
the  granite,  such  as  joint-planes,  have  served  as  barriers  to  in- 
definite impregnation.  On  the  other  hand,  the  breccia,  not 
being  composed  of  a  crystalline  granular  material,  but  being 
built  up  by  fragments  which  are  confusedly  mingled  together, 
has  no  defined  system  of  joints,  and  the  width  of  the  impreg- 
nation which  constitutes  the  ore  will  be  determined  by  purely 
local  conditions  of  fracture ;  the  lodes  may  have  no  walls,  and, 
when  they  are  limited  by  such  boundaries,  these  are  apt  to  be 
cracks  sympathetic  with  the  main  vein-fractures  and  parallel  to 
them.  In  the  phonolite  the  limits  are  set  up  by  the  sheeting 
of  that  rock ;  the  ore,  which  is  infrequently  found  in  phonolite, 
occurs  then  as  a  lining  or  powdery  encrustation  upon  the  faces 
of  the  laminae,  and  not,  as  a  rule,  within  the  matrix  of  the 
rock  itself.  As  the  lamination  is  parallel  to  the  walls  of  these 
dikes,  the  width  of  ore  also  has  a  shape  conforming  to  them. 

Faulting  on  a  large  scale  is  conspicuously  absent  in  the  mine- 
workings  ;  that  is  to  say,  there  is  no  evidence  of  extensive 
movement  since  the  ore  was  deposited.  Penrose  has  recorded 
his  opinion  that  "  the  fissures  represent  fault-planes  of  slight 
displacement."*  The  amount  of  this  displacement  is  not  meas- 
urable, because,  as  a  matter  of  fact,  the  multiplicity  of  the 
fracturing  and  the  subsequent  precipitation  of  ore  has  obscured 
it  most  effectually,  and  it  is  this  character  of  multiple  fracture 
which  pervades  the  entire  structure  of  the  volcanic  area.  To 
what  extent  these  fractures  are  merely  shrinkage-cracks  and 
to  what  extent  they  represent  radical  movements  due  to  the 
readjustment  around  a  volcanic  orifice,  I  cannot  say.  In  so  far 
as  the  question  concerns  ore-deposition,  one  can  emphasize  the 
fact  that  all  breaks,  from  a  crack  to  a  crevasse,  are  the  outward 
and  visible  signs  of  displacement;  for  without  displacement 

*  "Geology  and  Mining  Industries  of  the  Cripple  Creek  District,"  U.  S.  Geol. 
Survey,  p.  153. 


42  THE    LODES    OF    CRIPPLE    CREEK. 

the  fracture  is  only  latent,  and  a  latent  fracture  has  no  possi- 
bilities for  ore-deposition  and  does  not  concern  the  mining  ge- 
ologist. Since  the  ore  was  formed  conditions  of  comparative 
rest  must  have  supervened,  for  this  is  a  direct  inference  from 
the  comparative  absence  of  faults.  This  fact,  taken  with  the 
known  age  of  the  volcano,  which  broke  out  so  late  in  geologi- 
cal time  as  the  end  of  the  Eocene  or  early  in  the  Miocene 
period,  points  to  the  recency  of  the  agencies  which  made  the 
ore-deposits. 


BY  THE  SECRETARY.  —  Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other 
errors  or  communications  for  publication  as  u  Discussions,"  or 
independent  papers  on  the  same  or  a  related  subject,  are  earn- 
estly invited. 


SUBJECT  TO  EEVISIOX. 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


Vein- Walls. 

BY  T.  A.  RICKARD,  DENVER,  COLORADO. 
(Pittsburgh  Meeting,  February,  1896.) 

FROM  time  immemorial  the  fissure-vein  has  been  held  the 
simplest  type  of  ore-deposit.  The  prominence  given  to  it  by 
Cotta  and  his  disciples,  from  their  study  of  the  mines  of  the 
Erzgebirye,  is  impressed  upon  technical  literature;  and,  in 
in  consequence,  the  ores  which  carry  the  valuable  metals  have 
been  supposed  to  occur  mainly  in  fissures,  cleaving  the  rocks 
in  diverse  directions,  and  the  noblest  type  of  vein  has  been 
deemed  that  which  cut  across  the  country  independent  of  its 
structure,  whether  evidenced  as  bedding,  foliation  or  cleavage, 
and  which  was  identified  with  rents  produced  in  the  rocky  crust 
of  the  earth. 

As  so  conceived,  the  vein  was  a  fissure  filled  with  ore,  extend- 
ing through  the  country  for  a  varying  distance,  and  continued 
downward  to  a  depth  more  or  less  proportionate  to  its  longi- 
tudinal extent.  The  vein-material  was  bounded  by  an  encase- 
ment of  rock,  and  those  immediate  surfaces  which  limited  it 
on  either  side  were  called  "  walls." 

These  primary  conceptions  have  become  modified  by  the  ex- 
perience of  modern  mining  in  widely  separated  regions.  The 
study  of  lode-formations  has  led  to  the  recognition  of  notable 
departures  from  the  supposed  normal  structure  of  the  veins  of 
Saxony  and  Cornwall,  the  two  classic  homes  of  early  economic 
geology. 

Typically  the  walls  of  a  vein  are  conceived  as  parallel  rock- 
planes  enclosing  the  ore ;  the  upper  one  being  called  the  "  hang- 
ing," and  the  lower  the  "  foot-wall."* 

Walls  are  rarely  alike.  Even  where  a  vein  traverses  a 
homogeneous  formation,  such  as  a  massive  crystalline  rock,  it 
is  usually  found  that  the  surface  which  bounds  it  underneath 

*  The  French  equivalents  are  le  toit,  "the  roof,"  and  le  mur,  literally,  "the 
wall.''  In  German,  df(s  Hangende  and  das  Lieyende. 

1 


2  VEIN-WALLS. 

differs  from  that  which  limits  it  overhead.  This  is  to  be  as- 
cribed to  the  effect  of  the  agencies  which  brought  about  the 
deposition  of  the  ore.  The  action  of  underground  waters  tends 
at  first  to  affect  both  equally ;  but  in  many  cases  probably  the 
solutions,  as  they  slowly  ascend  along  the  line  of  fissuring,  are 
prevented  from  penetrating  into  the  encasing  rock  by  the  occur- 
rence of  an  impermeable  covering  of  clay,  due  to  abrasion, 
which  may  line  either  wall,  but,  because  of  gravity,  generally 
accompanies  the  under  one.  Similarly  we  are  justified  in  sup- 
posing that  the  deposition  of  a  mineral  deposit  may  form  a 
coating  which  would  serve  to  protect  the  fooi^wall  from  the  cor- 
roding effects  of  chemical  action.  The  activity  of  the  mineral- 
bearing  current  thus  becomes  diverted  in  its  greatest  intensity 
toward  the  upper  wall,  where  the  decomposition  of  the  rock- 
surface  may  be  followed  by  its  disintegration  so  as  to  cause  the 
exposure  of  fresh  faces  for  further  dissolution. 

Illustrations  of  these  conditions  may  be  seen  in  Figs.  1  and 
2.  The  first  is  reproduced  from  a  sketch  made  June  25,  1895, 
in  the  lower  level  of  the  Union  and  Companion  mine  at  Cornu- 
copia, Union  county,  Oregon.  It  represents  the  breast  of  the 
north  drift  on  the  west  vein.  The  country,  a  fine-grained 
granite,  is  not  visibly  altered  under  the  foot-wall ;  but  along  the 
hanging  it  exhibits  an  alteration  of  its  more  soluble  ingredients. 
There  is  a  slight  selvage,  D,  separating  the  granite  from  the 
pay-ore,  C,  which  is  about  10  inches  thick,  and  consists  of  rib- 
bons of  quartz,  impregnated  with  pyrite  and  alternating  with 
strips  of  altered  country.  A  distinct  parting,  unaccompanied 
by  any  apparent  selvage,  divides  this  streak  of  ore  from  one,  B, 
below  it,  which  is  twice  as  thick,  but  much  less  gold-bearing. 
This  part,  B,  of  the  vein  consists  of  white  quartz,  carrying  occa- 
sional patches  of  pyrite,  and  marked  by  large  inclusions  of 
slightly  altered  country,  arranged  along  the  foot-wall,  where  a 
thin  selvage  separates  them  from  the  outer  granite.  The  evi- 
dence of  vein-structure  embodied  in  this  figure  permits  diverse 
interpretations.  The  upper  pay-streak,  C,  appears  to  me  to  be 
country-rock,  in  place,  decomposed,  fractured,  and  silicified, 
with  accompanying  precipitation  of  gold.  The  central  wall 
may  have  been  the  original  hanging-wall.  The  present  foot- 
wall  is  sufficiently  distinct ;  but  the  occurrence  of  the  pieces  of 
enclosed  country  leads  me  to  believe  that  at  an  earlier  stage 


VEIN- WALLS. 


4  VEIN-WALLS. 

the  foot-wall  was  broken  and  irregular ;  the  shape  and  position 
of  the  fragments  of  rock  now  lying  upon  it  being  such  as  to 
render  it  doubtful  that  they  could  have  been  detached  from  the 
hanging. 

Fig.  2*  was  drawn  May  10,  1893,  in  the  ~No.  4  level,  north, 
of  the  Hillside  mine,  Yavapai  county,  Arizona.  The  lode  oc- 
cupies a  strong  fissure,  cutting  almost  vertically  through  the 
nearly  horizontal  layers  of  a  quartzose  talc  schist,  B  B.  The 
original  line  of  fracturing  is  probably  now  occupied  by  the 
seam,  C,  6  inches  thick,  of  white  talcose  clay,  covering  the  foot- 
wall.  The  ore-bearing  portion,  D,  of  the  lode  is  formed  by  an 
irregular  mineralization  of  the  hanging-wall  country,  extending 
to  a  distance  of  from  15  to  18  inches,  and  presents  an  intricate 
medley  of  quartz,  pyrite,  zinc-blende  and  a  little  galena,  carry- 
ing about  1  ounce  of  gold  and  25  ounces  of  silver  per  ton. 

The  most  noteworthy  feature  of  the  section  is  the  occurrence 
in  the  hanging,  on  the  outer  confines  of  the  main  ore-streak,  of 
several  irregular  cavities,  A  A,  whose  inner  surface  is  covered 
by  a  series  of  siliceous  coatings,  evidently  deposited  by  min- 
eralizing waters  that  have  circulated  through  them.  Along 
the  outcrop  of  the  lode,  at  Wikiup  Point,  there  occur  hollows 
in  the  schists,  of  a  character  similar  to  those  above  described, 
and  of  such  a  shape  as  to  suggest  that  their  origin  was  due  to 
the  removal,  by  waters  carrying  carbonic  acid,  of  certain  por- 
tions of  the  country,  rendered  soluble  by  the  segregation  of 
lime.  As  the  fourth  level  nearly  follows  the  water-level  of  the 
mine,  and  the  siliceous  encrustations  were  stained  with  iron 
oxide,  the  formation  appears  to  have  been  due  to  wThat  Posepny 
called  the  Vadose  circulation.  On  the  other  hand,  the  im- 
pregnation of  the  hanging-wall  country  by  sulphides  cannot  be 
ascribed  to  oxidizing  waters,  and  must  have  taken  place  at  an 
earlier  period,  when  the  surface  was  relatively  more  distant. 

The  lode  follows  a  fissure  formed  along  the  axis  of  a  syn- 
clinal bend  in  the  schists,  and  often  very  noticeably  reproduces 
the  structure  of  the  country  which  it  has  in  part  replaced ;  the 
ore  breaking  along  lines  corresponding  to  the  almost  horizon- 
tal foliation  of  the  schists.  The  width  of  the  ore  is  very  ir- 
regular. That  occasionally  found  under  the  clay  seam  is  rarely 
rich  enough  to  mine ;  the  main  pay-streak  being  that  portion 

*  See  also  Tram.,  xxiv.,  945. 


VEIN-WALLS. 


of  the  vein  bounded  underneath  by  the  clay  and  extending  into 
the  hanging  until  the  mineralization  becomes  so  meager  that 
"  ore  "  becomes  "  country-rock." 


Fig.  3. 


'LIMESTONE        (J 
CD  QUARTZ 


COARSE  SANDSTONE 


FINE  GRAINED  SANDSTONE 


•RHODOCHROS.TE      SORE 
ENTERPRISE    MINE,  COLORADO. 


When  a  vein  occurs  in  a  formation  composed  of  several  kinds 
of  rock  it  may  cut  across  the  lines  of  parting  and  be  labelled  a 
"  true  fissure  ;  "  or  it  may  conform  to  them,  and  become  a 


6  VEIN-WALLS. 

"  bedded  vein,"  if  the  two  beds  happen  to  be  similar,  or  a 
"  contact-vein,"  if  they  are  dissimilar.  It  is  evident  that,  when 
a  vein  crosses  the  bedding  of  a  series  of  sedimentary  rocks,  the 
differences  between  the  enclosing  walls  at  any  given  place  will 
depend  upon  the  thickness  of  the  beds  traversed,  and  the  ex- 
tent of  the  faulting  of  the  country  along  the  line  of  the  fissure. 
When  the  faulting  is  slight,  the  change  in  the  wall-rock  will  be 
practically  simultaneous  for  both  sides  of  the  vein ;  while,  when 
the  dislocation  is  equal  to,  or  exceeds,  the  thickness  of  the 
members  of  a  series  of  dissimilar  beds  so  intersected,  the  oppos- 
ing walls  may  be  entirely  dissimilar.  This  is  illustrated  in  Figs. 
3  and  4. 

Fig.  3  represents  the  breast  on  August  14, 1894,  of  the  north 
drift  of  the  Jumbo  ~No.  2  vein,  on  the  Group  tunnel  level,  in 
the  Enterprise  mine,  at  Rico,  Dolores  county,  Colorado.  The 
vein  follows  a  fault-fissure  through  a  series  of  lower  carbonifer- 
ous shales,  limestones  and  sandstones.  The  throw  of  the  fault, 
along  which  the  ore  has  been  deposited,  is  about  2  feet ;  the 
thickness  of  the  prominent  bed  of  limestone  is  3  feet ;  and  the 
section  shown  in  the  figure  covers  7  feet  by  6.  It  is  charac- 
teristic of  the  veins  in  this  mine  that  they  'split  up  and  be- 
come impoverished  in  lime,  while  in  the  sandstone,  on  the 
contrary,  they  usually  become  clean-cut,  compact  and  richly 
ore-bearing,  as  is  the  case  at  the  top  of  the  drift  represented 
in  the  figure.  In  traversing  the  lime,  the  selvage  following 
the  line  of  fissuring  is  very  noticeable;  but  in  the  sand- 
stone, particularly  where  the  vein  splits,  the  ore  is  "  frozen," 
that  is,  has  no  evident  parting  separating  it  from  the  encasing 
rock. 

Fig.  4  is  taken  from  a  drawing  accompanying  a  note  by  Mr. 
E.  J.  Dunn,  of  the  Victorian  mining  department,  contributed 
by  him  to  the  Quarterly  Report  of  December  31, 1888.  It  rep- 
resents certain  features  of  the  Sunday  reef,  near  Beechworth  in 
Victoria  (Australia).  The  country  consists  of  Silurian  slates 
and  sandstones,  which  have  been  faulted  about  2  feet.  Along 
this  line  of  faulting  gold-bearing  quartz  has  been  deposited ; 
and  it  is  noticeable  that  its  occurrence  is  mainly  confined  to  the 
under  side  of  the  sandstone,  while  under  the  slate  it  disappears 
and  gives  place  to  fluccan  or  clay.  I  would  suggest  that  the 
lenticular  shape  of  the  quartz-bodies  indicates  that  the  spaces 


VEIN-WALLS. 


i? 


8  VEIN-WALLS. 

occupied  by  them  were  produced  by  the  movement  of  one  of 
the  walls  of  a  fissure,  following  a  line  whose  undulatory  form 
was  caused  by  the  unequal  texture  and  hardness  of  the  beds 
traversed  by  it. 

Of  the  change  observable  in  the  character  and  value  of  the 
mineral  ingredients  of  a  vein  in  its  passage  from  one  kind  of 
rock  into  another  it  is  hardly  possible  to  speak  in  parenthesis. 
One  of  the  best  known  examples  is  that  of  the  old  Dolcoath 
mine  in  Cornwall,  where  the  vein,  in  leaving  the  clay-slate 
(killas)  and  penetrating  the  granite,  changed  from  a  copper- 
bearing  into  a  tin-bearing  lode.  I  might  also  mention  the  sil- 
ver-lead veins  of  Pontgibaud,*  in  France,  which  are  in  a  gneiss 
country,  diversified  by  dikes  of  granulite.  The  ore-veins  have 
been  formed  along  fractures  within  the  dikes,  and  on  their  line 
of  contact  with  the  gneiss.  When  the  dike  diminishes  in  size, 
the  ore  decreases  in  width ;  when  the  vein  penetrates  into  the 
gneiss,  the  ore  disappears.  The  best  ore  is  associated  with  the 
kaolinization  of  the  feldspar  of  the  granulite ;  and  when  the 
latter  becomes  hard  and  unaltered  in  depth,  the  ore  pinches 
out. 

On  Newman  Hill,  Rico,  Colorado,  the  veins  of  rich  gold-  and 
silver-bearing  ores  are  noticeably  affected  by  the  character  of 
their  rock-walls.  The  particular  changes  due  to  penetrating 
from  lime  into  sandstone  have  already  been  mentioned  in  con- 
nection with  the  veins  of  the  Enterprise  mine,  but  there  is  also 
the  more  general  observation,  that  when  the  sedimentary  beds 
are  black,  the  veins  in  them  are  rich ;  when  they  lose  that 
black  color,  the  ore  diminishes. 

Other  instances  occur  to  me,  but  the  above  are  typical.  This 
inter-dependence  between  country  and  ore  has  been  used  as  an 
argument  in  support  of  the  now  crippled  lateral-secretion 
theory.  It  has  been  suggestedf  that  this  relation,  often  no- 
ticed in  vein-mining,  points  to  the  derivation  of  the  ore  from 
the  enclosing  rock,  and  that  some  formations  have  an  enriching 
effect,  because  they  have  been  the  source  of  the  valuable  metals 

*  See  "  The  Lodes  of  Pontgibaud,"  by  the  writer,  in  the  Eng.  and  Mm.  Jour. 
of  August  11  and  18,  1894. 

f  As,  for  instance  in  the  paper  ' '  On  Some  Evidences  of  the  Formation  of  Ore- 
Deposits  by  Lateral  Secretion  in  the  John  Jay  mine,  at  Providence,  Boulder 
county,  Colo.,"  by  P.  H.  Van  Diest,  in  the  Proceedings  of  the  Colorado  /Scientific 
Society,  vol.  iv.,  p.  340,  and  in  the  discussion  of  the  said  paper,  Id.,  p.  340. 


VEIN-WALLS. 


o 


10  VEIN-WALLS. 

now  found  in  the  veins  penetrating  them.  But  as  Cotta  long 
ago  suggested,  the  influence  of  the  physical  texture  and  chemi- 
cal composition  of  the  country,  as  facilitating  the  deposition  of 
the  ore,  may  explain  this  phenomenon.  The  former  would  affect 
the  rate  of  cooling  and  the  formation  of  adhesive  crusts.  The 
latter  would  act  by  direct  chemical  precipitation. 

As  I  suggested  in  the  discussion  of  the  paper  just  referred  to, 
the  local  enrichment  or  impoverishment  of  veins  may  be  ex- 
plained by  the  presence  or  absence  in  the  enclosing  formation 
of  precipitating  agents.  What  the  agent  has  been  we  can  only 
in  rare  instances  guess.  At  Rico  it  was  undoubtedly  the  car- 
bonaceous matter  enclosed  in  the  Lower  Carboniferous  shales, 
limestones  and  sandstones.  At  Pontgibaud  it  was  probably  the 
feldspar  which  made  room  for  the  silver-bearing  galena,  and  in 
Cornwall  also  the  beautiful  pseudomorphs  of  tinstone  after 
feldspar  suggest  similar  chemical  interchanges. 

In  the  case  of  veins  which  lie  along  the  bedding-planes  of 
sedimentary  rocks,  the  dissimilarity  between  the  enclosing 
walls  may  not  go  further  than  a  slight  difference  in  the  grain 
of  two  beds  of  sandstone,  the  color  of  two  beds  of  slate,  etc.,  or 
it  may  reach  the  more  marked  diversity  presented  by  rocks  as 
entirely  unlike  as  a  quartzitic  sandstone  and  a  soft  slate. 

Fig.  5  represents  a  gold-vein,  following  the  bedding  of,  and 
encased  by,  a  band  of  black  slate,  which  is  in  turn  flanked  on 
either  side  by  light  gray  slates.  The  ore  consists  of  ribbons  of 
quartz,  mingled  with  strips  of  included  country,  and  separated 
from  the  outer  slates  by  a  selvage,  faint  on  the  hanging-  but 
strong  on  the  foot-wall.  The  drawing  was  made  July  3,  1895, 
in  the  upper  level  of  the  Bonanza  mine,  Baker  county,  Oregon. 

The  comparatively  straight  walls  of  ordinary  vein-mining 
occasionally  give  place  in  veins  of  the  bedded  class  to  surfaces 
having  a  marked  curvature.  Such  walls  characterize  the  sad- 
dle-reef, a  type  of  lode-structure  common  in  only  two  known 
mining  districts,  namely,  Bendigo  in  Australia  and  Waverly  in 
Nova  Scotia — unless  it  be  true,  as  is  now  stated  on  good  au- 
thority, that  the  Broken  Hill  lode  in  New  South  Wales  is  also 
a  saddle-reef. 

In  these  regions,  gold-bearing  quartz  is  found  along  the  bed- 
ding-planes of  folded  sedimentary  rocks.  While  anticlinal 
folds  (or  saddles)  alternate  with  synclines  (inverted  saddles  or 


VEIN-WALLS. 


11 


+  L    +J-,*"!.    V    •**  *     4-  f.  ,  -r  4-  ,       *•   ^— — -C v 

-^>j^i±^S^<^;^ 

v     v    ^ 


12  VEIN-WALLS. 

troughs),  experience  has  shown  that  the  ore-deposition  is  mainly 
confined  to  the  former.  Such  a  formation  will  offer  many 
striking  features,  because  of  the  occasionally  very  regular  cur- 
vature of  the  walls.  I  remember,  for  instance,  standing  in  the 
stopes  just  above  the  980-foot  level  in  the  Johnson's  mine  at 
Bendigo,  and  seeing  the  foot-wall  curve  underneath  like  the  top 
of  a  boiler,  while  the  hanging  arched  overhead  like  a  Roman 
bridge.  This  was  the  apex  of  a  saddle,  as  illustrated  in  Fig.  7, 
reproduced  from  a  sketch  made  at  the  time.*  The  lode  is  seen 
to  consist  of  white  quartz  about  2J  feet  thick,  separated  from 
the  overlying  sandstone  by  a  very  regular  parting  of  black  clay. 
Underneath  is  about  a  foot  of  sandstone,  then  a  dark  seam  of 
slate,  from  5  to  6  inches  thick,  whose  parting  from  the  next  bed 
of  sandstone  is  marked  by  streaks  of  quartz,  thinning  out  both 
east  and  west. 

The  downward  continuation  of  such  a  formation  (the  "  legs 
of  the  saddle  ")  presents  the  appearance  of  an  ordinary  bedded 
vein,  usually  marked,  however,  by  a  noteworthy  want  of  per- 
sistence of  ore  in  depth.  Of  the  many  drawings  illustrating 
such  veins  already  contributed  to  the  Transactions^  I  have  re- 
produced, in  Fig.  6,  the  breast  of  the  north  end  of  the  1990-foot 
level  in  the  Shenandoah  mine  at  Bendigo.  The  lode  carries  2 
feet  of  closely-laminated  quartz,  from  which  spurs  or  stringers 
go  off  into  the  underlying  sandstone.  The  hanging  shows  a 
gouge  or  selvage, J  separating  the  quartz  from  the  overlying 
slate. 

Many  veins  follow  the  contact  between  eruptive  dikes  and 
the  metamorphic  or  sedimentary  formations  which  they  have 
penetrated.  The  dikes  of  quartz-andesite  porphyry  traversing 
the  granitoid  gneiss  of  the  earliest  mining  districts  of  Colorado 
(in  Boulder,  Gilpiri  and  Clear  Creek  counties)  offer  many  ex- 
amples of  this  type  of  vein-structure.  In  such  cases  the  miner- 
alization may  often  be  found  to  have  spent  itself  on  the  more 

*  Octobers,  1890.     See  also  Trans.,  xx.,  506. 

f  By  the  writer  in  vols.  xx.  and  xxi. 

J  "Selvage,"  "gouge,"  "dig,"  "pug,"  "fluccan"  are  all  more  or  less  syn- 
onymous. "A  layer  of  soft  stuff"  would  cover  them  all.  It  is  perhaps  worthy 
of  notice,  however,  that  our  "  selvage,"  used  in  this  sense,  is  not  the  exact  syno- 
nym, as  it  has  often  been  supposed  to  be,  of  the  German  Saalband.  A  Saalband  is  a 
definite  wall,  as  distinguished  from  a  gradual  transition  from  vein-matter  into 
country-rock.  A  layer  of  soft  material  on  the  wall  is  a  Besteg. 


VEIN-WALLS. 


13 


^vV, 


i « 


'  v\-r  X I 


14  VEIfr-WALLS. 

soluble  porphyritic  igneous  rock,  rather  than  upon  the  less 
soluble  metamorphic.  The  walls  of  such  veins  will  vary,  as 
the  ore  deposition  has  followed  either  fractures  along  the  im- 
mediate contact,  or  those  which  ramify  into  the  body  of  the 
dike,  or  those  again  which  cut  across  the  latter,  where  its  irregu- 
lar outline  has  been  an  obstacle  to  the  main  line  of  fissuring. 
These  ideas  are  illustrated  in  the  diagrams  A,  B  and  C,  Fig.  8. 

The  California  mine,  in  Gilpin  county,  offers  many  examples 
of  such  vein-phenomena.  Figs.  9  and  10  represent  the  western 
ends  of  the  2000-foot  and  the  2100-foot  levels,  as  seen  on  July 
13,  1892.  In  the  first  the  vein  is  seen  to  lie  between  mica- 
schist,  on  the  foot,  and  "  porphyry,"  on  the  hanging.  The 
"  porphyry"  forms  part  of  a  dike,  17  feet  thick,  of  dacite  or 
quartz-andesite,  and  is  both  brecciated  and  much  decomposed 
near  the  lode,  from  which  it  is  separated  by  a  dark  band  of 
"  flint,"  which  consists  of  small  fragments  of  porphyry  ce- 
mented together  by  a  very  dark  chalcedonic  quartz.  Under- 
neath this  there  are  5  inches  of  white  kaolinized  porphyry, 
containing  threads  of  iron  and  copper  pyrites.  Next  comes  an 
inch  and  a-half  of  quartz  and  feldspar  intermingled ;  then  a  band 
of  included  country,  part  gneiss  and  part  mica-schist,  which  is 
subdivided  by  a  streak  of  pyrite.  Finally  there  is  an  irregular 
foot-wall ;  the  load-filling  shading  off  into  the  soft  mica- 
schist  which  underlies  the  vein. 

The  lower  level,  shown  in  Fig.  10,  exhibits  a  marked  differ- 
ence. The  lode  has  crossed  the  dike,  and  the  porphyry  forms 
the  foot-wall.  Next  comes  a  thickness  of  6  to  8  inches  of  white, 
soft,  decomposed  porphyry,  then  a  black  selvage,  with  slicken- 
sides  on  the  lower  side.  Then  come  two  bands  of  mineralized 
porphyry,  separated  by  thin  partings.  The  main  width  of  ore 
consists  of  about  2  feet  of  lode-filling  traversed  by  patches  and 
streaks  of  pyrite.  Fragments  of  porphyry  can  also  be  recog- 
nized in  it.  This  is  separated  from  the  overhanging  gneiss 
and  mica-schist  by  a  selvage  of  varying  thickness. 

In  the  neighboring  Indiana  claim,  the  California  vein  exhib- 
its certain  changes,  the  most  evident  of  which  are  the  absence 
of  selvages,  the  indistinctness  of  its  limits  and  the  brecciation 
of  the  vein-filling.  This  is  suggested  in  Fig.  11,  which  repre- 
sents the  breast  of  a  stope  above  the  800-foot  level  west,  as  ob- 
served November  13,  1895.  The  enclosing  country,  A  A,  is  a 


VEIN-WALLS. 


15 


granite  almost  destitute  of  mica.  The  part  B  is  bespattered 
with  pyrite.  The  best  ore  is  a  seam,  C  C,  of  black  zinc-blende 
lining  the  hanging-wall.  D  is  evidently  brecciated.  The 
larger  part  of  the  section  consists  of  slightly  altered  country  (E 
E)  reticulated  with  seams  of  blende,  following  joint-fractures. 
The  foot-wall  of  the  vein  is  considered  to  be  under  the  bands  of 
zinc-blende  and  copper  pyrites  occurring  along  F  F.  The  en- 


Rg. 


tire  width  is  about  4  feet.  The  lode  has  departed  from  the 
dike,  with  which  it  is  so  closely  associated  in  the  neighboring 
mine ;  but  the  workings  show  that  it  meets  this  dike  at  inter- 
vals, and  is  benefited  by  the  intersection. 

That  the  vein  follows  the  line  of  a  fault  can  be  seen  by  ex- 
amining the  walls  of  the  2000-foot  level  in  the  California  mine, 
more  particularly  at  points  between  350  and  450  feet  west  of 
the  shaft,  where  the  lode  has  left  the  dike  entirely,  and  is  en- 
cased in  the  gneiss  and  mica-schist.  The  country-rock  on  the 
two  sides  of  the  drift  is  not  the  same.  The  extent  of  the  throw 
of  the  fault,  however,  could  not  be  measured. 


16  VEIN-WALLS. 

In  the  course  of  the  foregoing  descriptions  of  lode-structures, 
mention  has  been  repeatedly  made  of  the  occurrence  of  clay 
selvage,  following  sometimes  one,  sometimes  both,  of  the  walls 
of  a  vein.  This  "  clay  "  may  occasionally  be  material  precipi- 
tated from  solution ;  ordinarily  it  is  only  crushed  rock.  It  fre- 
quently encloses  exquisite  mineral  specimens,  because  its  soft 
consistency  has  permitted  untrammeled  crystalline  growth. 
Most  examples  of  well-developed  crystals  of  native  gold  have 
been  discovered  under  such  conditions.  This  is  the  case  at 
Cripple  Creek,  Colo.,  where  the  gouge  or  clay  has  been  dried 
and  hardened  near  the  surface,  and  as  a  crumbly  earth,  made 
purple  by  the  presence  of  fluorite,  carries  beautiful  crystals  of 
gold  pseudomorphic  after  sylvanite  and  calaverite.  The  exquisite 
leaf-gold  specimens,  for  which  Farncomb  hill  (Breckenridge, 
Summit  county,  Colo.)  is  so  famous,  are  found  imbedded  in 
talcose  clay.  Large  pieces  of  pure  argentite  are  often  found  in 
such  an  environment,  as  at  the  De  Lamar  mine,  in  Owyhee 
county,  Idaho.  Wire-silver  also  has  been  found  in  compara- 
tively large  amount  encased  in  such  a  "  mud  "  in  many  Lead- 
ville  mines;  notably  at  the  Crown  Point,  in  1886. 

By  reason  of  their  opposition  to  the  passage  of  water  such 
seams  of  clay  protect  the  rock-surface  of  vein-walls,  and  under- 
neath them  there  will  occasionally  be  found  comparatively  fresh 
and  unaltered  rock  having  beautifully  polished  faces  or  slicken- 
sides.  At  Ballarat,  in  Australia,  I  have  seen  many  such  rock- 
faces  like  finished  ivory  in  their  smoothness,  and  streaked  with 
black  lines,  due  to  the  grinding  of  specks  of  pyrite.  In  the 
Bonanza  mine,  Baker  county,  Ore.,  there  could  be  seen  quite 
recently  an  exquisite  example  of  such  an  occurrence.  In  an 
upper  drift  there  was  at  one  place  a  surface  of  a  few  feet  square 
(on  one  of  the  Avails  of  a  gold-bearing  quartz-vein)  covered  by 
a  thin  layer  of  black  clay,  under  which  lay  what  seemed  a  white 
enamel  of  very  remarkable  delicacy.  It  could  not  be  removed 
without  breaking,  because  it  was  very  friable,  consisting  essen- 
tially of  crushed  quartz  partially  recemented,  probably  by 
pressure. 

"  The  handwriting  on  the  wall "  is  not  always  easy  to  deci- 
pher. The  lines  or  striae  occasionally  to  be  seen  upon  its  sur- 
face have  been  held  to  indicate  the  direction  of  that  movement 
(or  succession  of  movements)  of  the  opposing  rock-planes  to 


VEIN-WALLS. 


17 


which  the  deposit  of  ore  primarily  owed  the  opportunity  for  its 
existence.     These  lines,  however,  sometimes  have  opposite  di- 


\--\- 


rections  within  a  short  distance  and  otter  conflicting  evidence 
hard  to  explain. 

2 


18  VEIN-WALLS. 

Rarely  is  a  story  told  more  clearly  than  in  the  ripple-marked 
foot-wall  which  was  to  be  seen  in  October,  1891,  in  the  John- 
son's mine  at  Bendigo.  It  had  been  very  difficult  to  distinguish 
the  bedding  of  the  country  because  the  development  of  a 
strongly-marked  cleavage  had  obliterated  the  lines  of  original 
sedimentation.  At  the  106 5-foot  level,  however,  the  matter  was 
made  plain.  For  more  than  100  feet  square  the  surface  of  the 
foot-wall  was  covered  with  ripple-markings.  The  crests  of  the 
waves  were  about  3  inches  apart  and  presented  all  the  little  ir- 
regularities to  be  seen  to-day  when  the  wind  blows  over  the  shal- 
low waters  of  an  estuary  and  imprints  the  evidence  of  its  action 
upon  the  yielding  sand.  The  markings  had  been  protected 
by  layers  of  Silurian  sediment,  and  the  whole  series  had  been 
indurated  into  rock,  the  sand  which  bore  the  markings  becom- 
ing quartzitic  sandstone,  and  the  overlying  mud  slate.  Between 
them,  as  within  the  pages  of  a  book,  was  preserved  the  conclu- 
sive evidence  of  the  original  position  of  the  beds  of  rock  enclos- 
ing the  reef,  which  had  been  formed  in  later  times,  when  fissur- 
ing  had  made  room  for  the  circulation  of  underground  waters 
and  the  deposition  of  the  gold-bearing  quartz. 

In  the  above  interesting  case  the  corrugation  of  the  foot-wall, 
due  to  the  ripple-markings,  rendered  difficult  the  detachment 
of  the  ore.  Distinct  walls,  especially  when  accompanied  by 
selvage,  are  very  useful  in  actual  mining ;  but  they  are  not  by 
any  means  necessarily  indicative  of  a  productive  vein,  or  par- 
ticularly favorable  to  the  continuity  of  the  ore.  A  "  clean  " 
wall  and  a  good  "  gouge  "  are  welcomed  by  the  miner  because 
they  ease  his  toil ;  but  the  idea  that  their  presence  alongside  a 
lode  gives  it  a  character  better  than  another  unprovided  with 
such  adjuncts  is  a  dangerous  delusion.  In  many  mines,  more 
ore  has  been  lost  through  the  persistent  following  of  a  "  wall," 
without  exploring  beyond  it,  than  was  ever  compensated  for  by 
the'  greater  facility  given  by  such  a  parting-plane  for  the  break- 
ing of  the  ore  found. 

Many  veins  have  no  defined  walls,  but  gradate  imperceptibly 
into  the  enclosing  country,  and  are  bounded  only  by  the  com- 
mercial value  of  the  material  mined.  Such  veins  are  to  be 
seen,  for  instance,  in  the  mountains  that  overlook  Silver  Plume, 
Clear  Creek  county,  Colo.  Fig.  12  represents  a  sketch  made 
May  27,  1892,  from  the  300-foot  level  of  the  Seven-Thirty  mine. 


VEIN-WALLS. 


19 


A  fracture  penetrating  the  metamorphic  granite  carries  ore  on 
both  sides,  which  diminishes  in  richness  as  it  spreads  into  the 
encasing  country.  The  joints  in  the  granite  are  evident. 

In  this  mine  the  so-called  "  walls "  are  often  simply  two 
parallel  veins  (rich,  but  very  small),  separated  by  clean,  hard 
country.  This  is  illustrated  in  Fig.  13,  which  was  obtained 


Fig.  14. 


CANTON   MINE 

from  the  same  level  about  1000  feet  further  east,  The  grani- 
toid gneiss  is  traversed  by  two  streaks  of  ore,  of  which  the  one 
to  the  right  is  much  the  richer.  Between  them  there  are  at 
least  two  well-marked  parallel  fractures  devoid  of  ore.  The 
vein  to  the  left  has  a  thin  selvage,  under  which  there  is  a  streak 
of  quartz  carrying  a  little  silver-ore;  but  the  companion-vein  to 
the  right  follows  a  fracture,  unaccompanied  by  any  selvage, 
whose  upper  side  is  impregnated  with  about  3  inches  of  tetra- 
hedrite,  galena,  and  polybasite. 


20  VEIN-WALLS. 

Where  ore  is  absent  in  the  Seventy-Thirty  mine,  the  walls 
are  apt  to  be  particularly  well-defined  ;  and  when  there  is  any 
thickness  of  rich  silver-bearing  mineral  present,  the  walls  are 
scarcely  to  be  distinguished,  and  the  rock  is  hard  to  break,  be- 
cause it  is  destitute  of  convenient  partings.  The  large  veins 
carrying  gouge  are  found  to  be  uniformly  poor,  except  where 
they  meet  the  very  narrow  rich  streaks  which  constitute  the 
resource  of  the  property.  The  Seven-Thirty  vein  proper  is 
only  2  J  inches  thick,  but  it  is  very  persistent  through  the  midst 
of  hard  crystalline  rocks,  and  it  has,  for  twenty  years,  proved 
very  productive. 

In  many  mines  one  vein  only  is  exploited,  and  cross-cutting 
the  country  in  search  for  parallel  lodes  is  entirely  neglected. 
In  others,  a  cross-cut  is  stopped  as  soon  as  it  reaches  the  further 
wall  of  the  particular  vein  it  was  started  to  reach.  Both  these 
unwise  practices  are  founded  upon  a  misconception  of  lode-struct- 
ure, due  to  a  narrow  interpretation  of  the  early  teachings  of 
economic  geology,  which  lays  a  misleading  emphasis  upon  the 
definition  and  clean-cut  boundaries  of  so-called  "  true  fissure- 
veins."  The  fact  is,  as  daily  observation  proves,  that  there*  are 
walls  within  walls,  and  walls  beyond  walls ;  and  that  to  follow 
closely  any  particular  hard,  smooth  rock-surface,  with  the  idea 
that  it  is  the  utmost  limit  of  ore-occurrence  in  any  particular 
mine,  is  to  be  blind  to  the  realities  of  geological  structure. 

Fig.  14  represents  the  face  of  a  drift*  in  the  Canton  mine, 
near  Waipori,  Otago,  New  Zealand.  A  A  is  the  reef,  a  vein 
of  quartz  which  is  supposed  to  lie  immediately  upon  the  foot- 
wall.  Along  B  B  the  quartzose  schist  is  soft,  and  the  included 
quartz-folia  are  much  twisted.  C  C  is  one  of  .the  so-called 
"  false  hanging-walls."  Along  A  A  and  C  C  faulting  is  evi- 
dent, along  B  B  distortion  only.  It  was  not  possible  to  say 
where  the  lode  ended,  or  where  it  began.  The  whole  width 
from  A  to  C  was  known  to  be  gold-bearing,  although  A  A 
served  as  a  guide  in  following  the  gold-bearing  channel. 
Nevertheless  those  who  were  working  the  mine  had  little  com- 
prehension of  the  formation,  particularly  of  its  essential  lack 
of  definition,  and,  while  admitting  that  there  were  several 
"  false  hanging- walls,"  insisted  that  there  was  only  one  foot- 
wall  (underneath  A  A)  which  was  stated  to  be  of  a  different 

*  On  November  15,  1890.     See  also  Trans.,  xxi. ,  415. 


VEIN-WALLS. 


21 


kind  of  rock,  and  exceptionally  hard.  On  examination  I  found 
that  the  rock  of  the  supposed  foot-wall  was  similar  to  that  of 
of  the  rest  of  the  gold-bearing  country  forming  the  lode,  and 
on  a  sample  of  it  being  crushed  and  tested  in  a  prospector's 


Fig.  15. 


+•  t- 


GRANITE  ///     PYRITES 

^    SELVAGE  AND  CRUSHED  ROCK 


RIBBON  QUARTZ 
\Z?\    QUARTZ 


UNION  AND  COMPANION    MINE,  OREGON. 

pan,  it  was  discovered  to  be  richer  than  that  which  was  being 
actually  mined.  It  was  scarcely  necessary  after  that  to  insist 
that  a  cross-cut  should  be  made  into  the  foot-wall. 

Fig.  15  represents  the   north  breast*  of  the  lower  level  on 
the  main  lode    in    the   Union    and  Companion    mine,   Union 

*  On  June  26,  1895. 


22  VEIN-WALLS. 

county,  Oregon.  It  illustrates  the  occurrence  of  "  walls  within 
walls,"  for  while  the  lode  may  be  limited  by  the  main  boundaries 
along  E  and  D,  there  are  at  least  two  partings  (G  and  H)  equally 
well-defined,  subdividing  the  enclosed  width  of  ore.  The  coun- 
try is  a  fine-grained  granite,  which,  near  the  hanging,  is  de- 
composed and  ore-bearing.  D  is  a  streak  of  granular  crushed 
country,  mixed  with  lenticles  of  white  quartz  whose  longer 
axes  are  parallel  to  the  lode-walls.  D  is  from  3  to  7  inches 
wide,  and  carries  only  traces  of  gold.  A  consists  of  white 
hackly  quartz  spotted  with  iron  pyrites.  It  is  from  14  inches 
to  2  feet  wide,  and  contains  about  J  an  ounce  of  gold  per  ton 
of  ore.  Then  comes  a  hard  regular  "wall,"  separating  A  from 
B,  which  is  the  main  pay-streak,  ribboned  with  veins  of  iron 
and  copper  pyrites.  The  width  is  from  2J  to  3  feet,  and  the 
ore  averages  about  2  ounces  in  gold  and  8  ounces  in  silver. 
Then  follows  a  parting  marked  by  a  slight  selvage,  underneath 
which  comes  a  10-  to  15-inch  band  (C)  of  ribboned  white  quartz, 
stained  by  the  oxidation  of  copper  pyrites  and  carrying  about  5 
pennyweights  of  gold  per  ton.  Then  comes  the  main  foot-wall 
with  its  streak,  1  to  3  inches  thick,  of  granular  crushed  country, 
mixed  with  clay.  The  underlying  rock  is  but  little  altered. 

Fig.  16  affords  an  example  of  "  walls  beyond  walls."  It  rep- 
resents a  section  obtained  at  the  station  on  the  500-foot  level  in 
the  Mammoth  mine,  Final  county,  Ariz.  The  Mammoth  lode 
traverses  hornblende-granitite,  porphyrite  and  a  porphyry 
agglomerate.  The  lode-filling  consists  of  altered  country,  and 
therefore  changes  as  the  lode  in  its  strike  penetrates  first  one 
kind  of  rock  and  then  another.  When  standing  in  the  stopes 
it  is  not  difficult  to  recognize  in  the  ore  the  reproduction  of  the 
habit  of  either  the  granite  or  the  porphyrite  by  whose  altera- 
tion the  lode  was  produced.  The  country  near  the  lode  is 
much  altered  and  often  visibly  gradates  into  the  ore,  while,  as 
the  lode  is  receded  from,  these  effects  diminish  until  they  be- 
come confined  to  the  faces  of  the  rock  lining  the  fractures.  The 
granitite  carries  two  feldspars,  of  which  the  pink  orthoclase  is 
evidently  more  stable  and  succumbs  to  decomposition  less 
quickly  than  the  green  plagioclase.  The  ore  is  both  gold-  and 
silver-bearing,  but  chiefly  valuable  for  gold.  The  great  variety 
of  associated  minerals  includes  some  uncommon  species,  such 
as  wulfenite  (usually  colored  by  vanadic  acid),  vanadinite,  des- 


VEIN-WALLS. 


23 


cloizite,  ecdemite,  dechenite,  linarite,  besides  the  commoner 
anglesite,  pyromorphite,  cerussite,  malachite,  dioptase,  azurite, 
and  a  little  galena  and  pyrite.  Referring-  to  the  drawing  (made 
March  17,  1893),  the  edge  of  the  ore  is  shown  at  A;  it  becomes 

Fig,  16. 


GRANITITE 


VEIN  QUARTZ 


SELVAGE 


(/?/&j  GRANULAR  FILLING  , 

MAMMOTH   MINE,  ARIZONA. 

mixed  with  altered  granular  country  (along  B)  in  approaching 
the  "main  footwall."  This  is  followed  by  the  granitite  itself, 
in  which  there  are  well-defined  walls  (or  fractures  parallel  to 
the  lode-channel)  and  cross-joints,  often  lined  with  exquisite 
crystals  of  vanadinite  and  wulti'iiite. 

Going  to  the  Pacific  coast,  Fig.  17  represents  a  part  of  the 
west  side  of  the  so-called  "  mother  lode  "  of  California.     The 


24  VEIN-WALLS. 

drawing,  made  May  21, 1891,  is  a  portion  of  the  face  of  a  large 
open  cut  at  the  Gold  Cliff  mine,  Angel's  Camp,  Calaveras 
county,  Cal.,  near  the  now  well-known  Utica  mine.  The  ore- 
channel  consists  of  a  country-rock  traversed  by  cross-veins  of 
white  gold-bearing  quartz.  The  country-rock  is  a  greenish 
gray  augite  schist  (probably  at  one  time  a  diabase),  carrying 
coarse  pyrite  near  the  gold-quartz. 

There  are  "  walls  "  ad  infinitum.  Each  cuts  off  the  quartz- 
seams,  which  occur  again  on  the  further  side  and  extend  to  the 
next  "  wall,"  where  they  are  terminated  as  before,  and  so  on. 
A  certain  portion,  20  to  30  feet  in  width,  of  this  channel  of 
country  is  rich  enough  to  work,  and  is  sent  to  the  mill,  but  the 
poorer  material  which  lies  beyond  it  has  an  identical  geological 
structure.  Of  course,  in  such  a  case  the  "  main  walls  "  will 
depend  for  their  determination  upon  commercial  rather  than 
geological  conditions. 

Another  case  in  point  is  presented  at  the  Cashier  mine  in 
Summit  county,  Colo.,  as  illustrated  in  Fig.  18,  which  shows  a 
part  of  an  open  cut  on  the  lode,  as  seen  August  22,  1895.  The 
latter  consists  of  altered  quartz-felsite,  rendered  porphyritic  by 
large  crystals  of  feldspar.  It  is  spoken  of  as  a  vein  45  feet  wide, 
having  a  hanging-wall  of  porphyry  and  a  foot-wall  of  lime.  The 
ore  is  said  to  be  penetrated  by  dikes  of  porphyry.  The  facts 
are  really  these :  A  certain  width  of  quartz  felsite  within  the 
neighborhood  of  its  contact  with  the  limestone  has  been  acted 
upon  by  mineral  solutions  which  probably  came  up  along  that 
contact.  There  are  no  walls,  the  porphyry  of  the  hanging  be- 
ing simply  the  rock  of  the  ore-channel  in  a  less  altered  condi- 
tion. The  feldspar  of  the  lode-rock  has  been  leached  out.  In 
the  cavities,  now  partially  filled  with  crystalline  quartz,  iron 
oxide  and  gold,  there  can  be  distinguished  the  outlines  of  the 
large  (J  to  1J  inches)  crystals  of  orthoclase  whose  removal 
made  the  rock  porous  to  circulating  waters.  The  mineraliza- 
tion is  indicated  by  the  softening  and  reddening  of  the  por- 
phyry and  is  most  marked  along  the  joints,  especially  where 
they  intersect.  There  are  occasional  portions  of  the  rock  com- 
paratively unaffected  by  the  leaching  agencies,  and  therefore 
appearing  as  hard,  unstained  nuclei  amid  a  mass  of  softer  red- 
dish ore.  It  is  these  that  are  locally  termed  "  horses "  and 
"  dikes  "  of  porphyry. 


VEIN-WALLS. 


25 


26  VEIN-WALLS. 

Lodes  subdivided  by  partings  parallel  to  their  outer  walls  (as 
in  numbers  1,  9,  10  and  12)  often  resemble  twin  veins  such  as 
are  actually  formed  by  the  temporary  parallelism  of  two  dis- 
tinct fissures  travelling  together  after  they  have  united.  Such 
a  case  is  shown  in  Fig.  19,  which  illustrates  the  union  of  the 
Old  and  New  Castletown  veins  as  seen  in  the  north  face  of  the 
500-foot  level  of  the  Drumlummon  mine,  Marysville,  Mont.  The 
country  is  clay  slate.  A  B  is  the  Old  Castletown  vein,  2J  feet 
wide.  B  C  is  the  New  Castletown,  2  feet  wide.  There  is  no 
selvage  on  any  one  of  the  three  walls,  but  each  is  marked  by 
soft,  crushed  and  foliated  slate. 

The  generous  lodes  of  silver-bearing  copper-ore  which  at 
Butte,  Mont.,  penetrate  the  granite  are  frequently  marked  by  a 
brecciation  of  the  encasing  country  and  are  accompanied  by  a 
mineralization  of  the  granite  far  beyond  the  walls  or  limits 
of  workable  ore.  In  the  300-foot  level  of  the  Gagnon  mine, 
374  feet  west  of  the  main  shaft,  a  cross-cut  shows  that  the 
lode-channel  extends  30  feet  north  of  the  supposed  foot-wall,  the 
enclosed  granite  being  broken  and  mineralized.  Beyond  this 
line  the  country  ceases  to  be  shattered  and  is  no  longer  impreg- 
nated with  ore,  but  is  comparatively  fresh,  hard,  normal  granite, 
with  a  blocky  fracture.  This  outer  foot-wall  of  the  lode-chan- 
nel is  marked  by  the  occurrence  of  some  ore-streaks  and  an  ac- 
companiment of  seams  of  clay,  as  is  shown  in  Fig.  20  (drawn 
September  15,  1895).  The  foot-wall  country  has  a  noticeable 
number  of  slips  or  joint-planes.  It  is  separated  from  the  lode- 
channel  by  a  thick  layer  of  tough  black  clay.  Then  comes  a 
zone  of  kaolinized  granitic  filling  traversed  by  irregular  veins 
of  zinc-blende  and  pyrite.  Another  clay-seam  divides  this  part 
of  the  section  from  a  band  of  mixed  white  quartz  and  granitic 
filling,  followed  by  altered  mineralized  granite,  ribboned  with 
veins  of  gray  quartz,  whose  southern  limit  is  a  third  seam  of 
black  clay.  Then  comes  crushed,  brecciated  granite,  diversi- 
fied by  quartz  and  occasional  evidences  of  ore,  which  extends 
to  the  main  pay-vein  (on  the  hanging)  which  has  been  the 
workable  part  of  the  deposit.  The  section  in  the  figure  repre- 
sents a  width  of  6  feet. 

Fig.  21  came  from  the  east  breast  of  the  1300-foot  level,  in 
the  same  mine.  It  is  a  representative  section  of  the  main  ore- 
bearing  vein.  Granite,  visibly  altered,  marks  the  northern 


VEIN-WALLS. 


27 


11 


28  VEIN-WALLS. 

edge  of  the  section,  which  is  the  foot-wall.  Upon  it  lie  a  few 
inches  of  breccia,  succeeded  by  8  inches  of  blende,  pyrite,  and 
enargite,  well  intermingled.  Then  come  3  feet  of  friable, 
mineralized,  light  gray  shattered  quartz,  giving  place  to  6  to  8 
inches  of  harder  quartz  streaked  with  veinlets  of  chalcopyrite 
and  bornite.  Upon  this  lies  a  foot  of  altered  granite  traversed 
by  streaks  of  quartz.  Then  18  inches  of  low-grade  ore,  con- 
sisting of  quartz,  pyrite,  blende  and  a  little  bornite,  separated 
from  the  main  pay-streak  by  6  inches  of  granitic  filling.  The 
main  pay-streak  is  from  5J  to  6  feet  wide,  and  consists  of  a 
massive  mixture  of  pyrite,  blende,  enargite  and  bornite,  carry- 
ing about  60  per  cent,  of  silica.  Between  this  and  the  hang- 
ing-wall there  is  2  or  3  feet  of  decomposed  broken  granite, 
showing  small  veins  of  ore  which  drop  into  the  main  pay-streak. 
Beyond  is  granite. 

In  mines  of  this  character,  the  geologist  may  determine  the 
existence  of  the  lode  far  beyond  the  limits  of  workable  ore ;  but 
the  miner  will  rightly  distinguish  between  what  is  mineralized* 
country  too  poor  to  exploit  and  the  concentrated  mineral  which 
will  yield  a  profit. 

That  straight  walls  are  not  the  necessary  adjuncts  of  a  vein 
of  ore  is  suggested  in  Fig.  22,  which  represents  the  breast  (on 
September  26,  1895)  of  the  hanging- wall  drift  on  the  upper 
level  of  the  Double  Extension  mine,  in  Summit  county,  Colo. 
The  lode-formation  consists  of  gently  sloping  quartzite,  cut 
across  and  broken  into  by  porphyry,  which,  as  a  dike,  forms 
"  the  main  vein,"  and  in  the  shape  of  sheets,  intercalated 
among  the  beds  of  quartzite,  makes  a  succession  of  "  floors  "  of 
gold-bearing  ore  of  widely  varying  hardness.  In  the  particular 
section  illustrated,  the  intrusive  porphyry  forms  the  hanging- 
wall,  A  B  C,  of  a  zone  of  ore  which  is  limited  on  its  lower  side 
by  the  ragged  edges  of  the  quartzite,  M  M.  In  this  instance 
the  conventional  straight  walls  give  place  to  one  of  extreme  and 
irregular  curvature  and  another  of  a  markedly  broken  and 

*  The  term  "mineralized,"  like  the  word  "mineral,"  is  employed  by  miners 
in  a  sense  not  sanctioned  by  the  ordinary  dictionary,  though  fully  entitled  by  its 
general  usage  to  such  recognition.  Dr.  Raymond's  Glossary  of  Mining  and  Metal- 
lurgical Terms  gives  this  sense  as  follows :  "Mineral.  In  miners'  parlance,  ore.  .  .  . 
Mineralized.  Charged  or  impregnated  with  metalliferous  mineral."  The  French 
use  mineral  and  mineraliser  in  this  sense  ;  and  I  have  adopted  it  because  no  English 
equivalent  occurs  to  me. 


VEIN-WALLS. 


29 


jagged  outline ;    but   they  are    nevertheless  walls,  as  truly  as 
would    be   the    most    perfectly   straight,    smooth   rock   faces. 


1 


mm 


The  porphyry,  A  C,  a  quartz-felsite,  is  bleached  to   a  yellow 
white  and  softened  to  a  granular  clay,  as  it  approaches  its  con- 


30  VEIN-WALLS. 

tact  with  the  broken  quartzite,  D  D.  The  latter  is  dark  bluish- 
gray,  and  carries,  along  its  joints  and  other  fractures,  minute 
seams  of  iron-stained  ocherous  clay,  which  is  gold-bearing.  E 
E  and  G  G  are  veins  of  such  gold-bearing  ocher.  F  F  is  crushed 
quartzite,  very  similar  to  D  D.  The  band  of  quartzite  breccia, 
H  H,  is  separated  from  an  equally  wide  band  of  porphyry- 
quartzite  breccia,  L  L,  by  a  succession  of  thin  parallel  quartz- 
seams,  K  K.  Then  comes  the  foot-wall  itself.  At  N",  under 
the  projecting  curve  of  the  porphyry  of  the  hanging,  there 
is  a  mass  of  much-shattered  quartzite  mixed  with  iron-stained 
quartz.  This  is  all  gold-bearing. 

Fig.  23,  representing  the  western  edge  of  a  "  cutting-out 
stope,"  near  the  supposed  foot- wall  of  the  lode  (as  seen  Septem- 
ber 23,  1895)  exhibits  a  somewhat  similar  complication  and 
another  curved  "  wall."  To  the  extreme  left  is  fractured  quartz- 
ite, carrying  iron-stained  clay  along  the  faces  of  fractures,  and 
divided  into  two  parts,  H  H  and  B  B,  by  a  narrow  zone,  A  A, 
of  soft  yellow  porphyry,  whose  curved  lines  of  alteration  are 
marked  by  streaks  of  gold-bearing  ocher.  The  remainder  of 
the  section  is  all  porphyritic  material,  of  which  C  C  is  similar 
to  A  A;  D  D  is  a  wedge  of  comparatively  fresh  rock,  but 
slightly  kaolinized  and  full  of  pyrite,  and  E  E  and  F  F  are  lay- 
ers of  brown  and  reddish  soft  talcose  porphyry  and  clay,  sepa- 
rated by  numerous  slips  or  smooth  partings  forming  "  false 
walls."  The  "  main  foot-wall  "  was  supposed  for  some  time  to 
be  the  line  of  contact  of  the  band  of  quartzite,  B  B,  with  the 
underlying  porphyry;  but  assays  have  shown  that  the  soft  de- 
composed rock  lying  beyond  it  is  fully  as  gold-bearing  as  the 
quartzite,  and  can  be  mined  with  as  much  profit  for  several 
feet  beyond  that  line. 

Not  infrequently  veins  have  irregular  indistinct  walls  when 
ore-bearing,  and  smooth,  clearly  defined  ones  when  barren. 
Fig.  24  illustrates  the  face  (as  seen  September  15,  1895)  of  the 
west  drift  of  the  430-foot  level  on  the  middle  vein  in  the  Nettie 
mine,  near  Butte  City,  Mont.  The  south  country  is  a  fairly 
hard,  reddish  granite,  which,  in  approaching  the  hanging,  be- 
comes soft  and  is  traversed  by  slips  or  joints.  On  the  hanging- 
wall  itself,  A  A,  there  is  a  seam  of  tough  black  clay,  in  which 
can  be  seen  frequent  films  of  minutely  crystalline  blende  and 
galena,  and  small  imbedded  shots  of  ore  and  rock.  This  over- 


VEIN-WALLS. 


31 


lies  a  filling  of  white  decomposed  granitic  material,  full  of  part- 
ings and  seams  of  black  clay,  such  as  C  C.  The  foot-wall,  B  B, 
is  also  marked  by  a  black  selvage.  Underneath  it  comes  com- 
paratively fresh  "  Blue-bird  "  granite. 


Fig.  24 


-t-^t 


•f- 


-f  -f 

+  "t  t-1*. 
-t-  ff»* 

s;.y  >1-  t  -1- 


GRANITE 


SELVAGE 


QUARTZ 


NETTIE  MINE,  MONTANA. 

A  few  feet  further  east  this  level  carried  an  ore-body,  A  B 
in  Fig.  24  being  the  zone  so  transformed.  The  brecciated 
quartz  upon  the  foot-wall  was  the  part  of  the  vein  which  first 
became  ore.  The  sides  of  the  drift  are  now  coated  with  a  deli- 
cate efflorescence  of  goslarite  (sulphate  of  zinc).  In  this  con- 


32  VEIN-WALLS. 

nection  it  may  be  of  interest  to  state  that  in  the  Gagnon  mine, 
at  Butte,  three  miles  away,  the  apparently  clean  country,  at 
some  distance  from  the  lode,  was  found*  to  carry  3  per  cent,  of 
zinc,  indicating  the  extent  to  which  the  mineralizing  action  had 
penetrated. 

Figs.  25  and  26  represent  an  interesting  piece  of  evidence. 
Fig.  25  is  an  attempt  to  reproduce  in  color  a  block  of  ore  giv- 
ing a  section  of  the  Jumbo  vein,  and  broken  in  the  Enterprise 
mine  a  year  ago.  It  is  a  beautiful  example  of  ribbon-structure. 
The  general  lode  arrangement  is  shown  in  Fig.  26,  from  a 
sketch  made  November  19,  1894.  The  vein  follows  a  line  of 
faulting,  nearly  at  right  angles  across  sedimentary  beds  of  alter- 
nating sandstone  and  limestone.  The  extent  of  the  fault  is 
clearly  marked  by  the  dislocation  of  the  bed  of  lime,  B  B,  and 
its  down-throw  of  about  2  feet  on  the  hanging-wall.  The 
country  on  the  foot  has  its  bedding-planes  turned  down,  while 
on  the  hanging  the  reverse  occurs. 

The  vein  is  about  a  foot  wide  and  is  composed  of  a  regular 
symmetrical  arrangement  of  diverse  minerals.  The  center  of 
the  ore  is  marked  by  a  seam  of  quartz.  The  most  remarkable 
feature  of  the  section,  however,  is  that  while  on  the  hanging 
the  ore  is  frozen  hard  to  the  sandstone,  on  the  foot  there  is  an 
actual  vacancy  separating  the  ore  from  the  country.  This  ex- 
tends for  a  few  feet  above  the  place  of  the  section,  and  is  seen 
to  find  its  downward  termination  as  soon  as  the  foot-wall  pene- 
trates into  limestone,  where  the  contact  of  the  ore  and  the  en- 
casing rock  is  only  marked  by  a  slight  selvage. 

This  description  will  render  more  intelligible  the  meaning  of 
the  detailed  section  of  the  vein  presented  in  Fig.  25,  which  is 
intended  to  portray  as  accurately  as  possible  the  characteristics 
of  the  ore-occurrence  at  the  point  in  the  lode  marked  A  on  the 
outline-drawing,  Fig.  26. 

The  main  features  are  as  follows :  The  western  boundary  of 
the  vein  is  fairly  straight,  dipping,  as  the  vein  does,  eastward. 
It  is  separated  from  the  country-rock,  a  light-gray  medium- 
grained  sandstone,  A  A,  by  an  actual  vacant  space,  B  B,  of 
about  half  an  inch.  The  edge  of  the  ore  nearest  the  foot-wall 
consists  of  an  irregular  band,  C  C,  of  about  f  of  an  inch  of 
quartz,  speckled  with  pyrite  and  chalcopyrite.  Toward  the  bot- 

*  According  to  Mr.  C.  W.  Goodale,  the  manager. 


nsi 
LI  1 1 


>      ? 

> 


VEIN-WALLS. 


33 


torn  this  quartz  narrows,  but  becomes  clearly  defined   into  a 
crystalline  comb,  with  teeth  at  right  angles  to  the  vein. 

Then  comes  a  zone,  D  D,  averaging  1 J  inches,  of  pink  rhodo- 
chrosite.  This  band  is  broken  into  by  veinlets  of  quartz,  some 
of  which  are  only  branches  from  the  outer  seam,  C  C,  while 
others  traverse  the  rhodochrosite  in  bluish-gray  streaks  parallel 


Fia  26 


to  the  general  structure,  and  are  peppered  over  with  particles 
of  pyrites. 

The  rhodochrosite  band  is  broken  on  the  right  by  the  irregu- 
lar outline  of  the  blende  and  galena,  E  E,  which  is  about  2 
inches  wide.  There  are  blotches  of  yellowish  "  resin-blende  " 
and  patches  of  bluish-black  galena  distributed  throughout  a  dark 
and  intricate  mixture  of  these  minerals.  They  shade  out  into 
the  white  quartz,  F  F,  which  makes  a  bilaterally  symmetrical 
division  in  the  ore.  The  dark  mass  of  the  sulphides  encloses 
shreds  of  rhodochrosite  having  distinct  outlines. 

3 


34  VEIN-WALLS. 

Along  the  median  line  of  the  central  quartz-seam,  F  F,  occurs 
a  succession  of  geodes,  lined  not  only  with  crystals  of  the  quartz 
itself  but  also  with  beautiful  crystals  of  stephanite.  The  latter 
are  seen  in  irregularly  distributed  clusters.  In  the  outer  quartz 
there  are  numerous  specks  of  pyrite. 

The  eastern  half  of  the  vein  presents,  in  reverse  order,  an  ex- 
act repetition  of  the  mineral  bands  just  described.  The  separa- 
tion between  the  rhodochrosite  band  and  the  outer  quartz  is 
more  distinct.  The  dark  sulphides  also  present  a  cleaner  out- 
line. The  outer  quartz  has  its  comb-like  structure  strongly  de- 
veloped, the  points  of  the  crystals  penetrating  into  the  pink 
rhodochrosite  and  their  base  gradating  into  the  dark-gray  sand- 
stone of  the  hanging-wall.  There  is  not  the  slightest  selvage  or 
parting  of  any  sort.  The  quartz  is,  as  the  miners  say,  "  frozen  " 
to  the  sandstone.  The  latter  is  marked  by  clouds  of  dark  min- 
eral hardly  denned  enough  to  be  described  as  dendritic.  This 
feature  is  traceable  to  the  diffusion  of  minute  particles  of  pyrite 
and  stephanite.  The  rock  is  rich  enough  to.be  classed  as  ore. 

In  interpreting  this  structure,  shall  we  follow  the  explana- 
tions given  for  the  repeating  symmetry  of  the  comb-structure  of 
the  Drei  Prinzen  vein,*  and  accept  the  theory  of  successive 
crystalline  growth  from  the  sides  of  a  gaping  crevasse  ?  Or 
are  we  to  conclude  that  the  mineral  aggregates,  now  forming 
the  ore,  were  derived  by  the  substitution,  bit  by  bit,  of  rock  in 
place  by  material  deposited  from  solutions  circulating  along  the 
line  of  fissuring  ? 

Do  we  conceive  of  veins  as  formed  by  the  filling  of  pre-exist- 
ing cavities,  whatever  their  shape  may  be,  produced  by  the 
rupturing  of  the  earth's  crust,  or  do  we  believe  that  lodes  can 
be  formed  without  any  previously  prepared  vacant  space  and 
simply  by  the  chemical  interchange  vaguely  covered  by  the 
term  metasomasis  ?  or,  again,  do  both  these  explanations  find 
corroboration  in  the  daily  observations  of  the  mine  ? 

*  As  drawn  by  Von  Weisenbach  in  his  book  published  at  Leipzig  in  1836. 
Other  notable  examples  of  this  structure  are  C.  Le  Neve  Foster's  drawing  of  the 
Huel  Mary  Ann  lode  (in  the  Transactions  of  the  Royal  Geological  Society  of  Corn- 
wall, vol.  xix.,  1875),  and  that  of  the  Carn  Marth  lode  by  J.  H.  Collins  (in  the 
Proceedings  of  the  Institute  of  Mechanical  Engineers,  1873).  Reference  may  also 
be  permitted  to  the  writer's  four  colored  drawings  of  the  Eureka,  Songbird,  Jumbo 
and  Kitchen  veins,  accompanying  a  paper  en  titled  "  Vein  Structure  in  the  Enter- 
prise Mine,"  in  the  Proceedings  of  the  Colorado  Scientific  Society  for  1895. 


VEIN-WALLS. 


35 


Walking  recently  along  the  railroad  grade    between  Ana- 
conda and  Cripple  Creek,  in  El  Paso  county,  Colorado,  I  found 


R 


in  the  sides  of  two  open  cuts  the  testimony  transcribed  in  Figs. 
27  and  28,  one  representing  a  typical  dike  and  the  other  a  typi- 


36  VEIN-WALLS. 

cal  ore-vein.  In  both  cases  the  country  is  the  coarse-grained, 
red  granite  of  the  Pike's  Peak  region.  In  both  the  jointing  is 
well  developed.  The  dark  dike  of  basalt  in  Fig.  27  cuts  clean 
through  the  red  granite.  Its  boundaries  are  clear,  there  is  no 
mistaking  the  line  of  separation.  Moreover  it  is  evident  that 
the  walls  have  duplicate  outlines  and  that  rupturing  has  sepa- 
rated them  without  the  destruction  of  their  definition.  The 
throw  of  the  fault-fissure  followed  by  the  dike  can  be  seen  to  be 
about  14  inches,  and  its  direction  is  indicated  by  the  arrow. 

Fig.  28,  sketched  in  the  immediate  neighborhood,  illustrates 
a  gold-bearing  vein  in  the  same  granite  formation.  Here  there 
is  no  essential  difference  between  the  country  and  the  vein-fill- 
ing. The  latter  is  altered  granite,  easily  recognizable  as  such, 
in  spite  of  its  having  become  granular  and  soft  through  the 
kaolinization  of  the  feldspar.  The  walls  of  the  vein  are  ill- 
defined,  the  streakiness  of  the  filling  being  dimly  repeated  in 
the  encasing  rock.  The  vein-filling  assays  $2.60  gold  per  ton 
at  this  place,  but  is  richer,  without  other  material  change  of 
character,  a  few  rods  distant. 

The  dike,  Fig.  27,  is  composed  of  foreign  matter  filling  an 
evident  fissure  ;  the  vein,  Fig.  28,  is  rock  in  place  changed  into 
ore  by  the  removal  of  some  of  its  constituents  and  the  substitu- 
tion of  new  ones.  In  the  former  case  liquid  material  rose  into 
the  fissure,  probably  pari  passu  with  its  formation.  On  the 
other  hand,  the  vein  of  gold-ore  traversing  the  granite  gives  no 
evidence  of  the  occupation  of  a  fissure  by  the  incoming  of  new 
material.  The  ore  is  granite  in  place,  softened,  decomposed, 
discolored,  and  impregnated  with  gold,  but  still  granite,  clearly 
enough.  Some  liquid  -more  subtle  than  molten  lava  was  the 
vehicle  which  brought  in  the  minute  particles  of  gold  and  re- 
moved the  alkali  of  the  feldspar.  It  was  water,  circulating 
for  long  periods,  and  patiently  searching  out  its  way,  which 
quietly  changed  the  granite  into  gold-bearing  ore. 

Is  it  necessary  in  this  case,  as  in  that  of  the  neighboring  dike, 
to  suppose  the  existence  of  an  open  fault-fissure  ?  The  evidence 
of  a  fault  along  the  course  of  the  vein  Cannot  be  discovered  with 
certainty  ;  nevertheless,  judging  from  analogy  and  experience, 
we  would  certainly  believe  that  the  gold  has  been  deposited 
along  a  line  of  displacement.  It  seems  difficult  to  conceive 
that  any  fracturing,  such  as  marks  the  beginnings  of  vein-forma- 


VEIN-WALLS. 


37 


tion,  can  take  place  without  some  displacement,  however  slight, 
of  the  two  opposing  rock-faces.  Without  such  dislocation, 
though  it  be  comparatively  insignificant  in  amount,  the  fracture 
is  only  latent,  and  can  hardly  be  said  to  exist.  The  possibility 
of  a  simple  rupture,  without  any  shearing  movement  or  relative 
displacement,  cannot  be  denied  ;*  but  observation  underground 
indicates  that,  so  far  as  the  deposition  of  ore  is  concerned,  we 


INDIANA  VEIN.  GILPIN  COUNTY.  COLORADO. 

have  invariably  to  deal  with  rupturing  accompanied  by  a  rela- 
tive displacement  of  the  rock-walls.  In  other  words,  veins  are 
generally  built  on  fault-lines.  The  absence  of  evidence  of  such 
movement  in  a  section  on  one  particular  plane  is  not  conclu- 
sive, since  the  displacement  may  have  been  at  right-angles  to 
the  section. 


*  In  this  connection  I  would  refer  the  reader  to  the  suggestive  paper  of  Mr. 
William  Glenn  on  "The  Form  of  Fissure-Walls,  as  Affected  by  Sub-fissuring,  and 
by  the  Flow  of  Rocks,"  read  at  the  Atlanta  Meeting  of  the  Institute,  October, 
1895,  and  printed  in  Trans.,  xxv.,  499. 


38  VEIN-WALLS. 

Where  a  vein  cuts  across  sedimentary  rocks,  the  dislocation 
may  be  looked  for  along  the  bedding-planes.  Such  is  the  case 
at  Rico,  in  the  Enterprise  mine  already  referred  to,  where  the 
breast  of  a  stope  will  show  a  vein  traversed  by  a  fracture  at  right- 
angles  to  its  walls,  and  apparently  unaccompanied  by  any  dis- 
location, but  further  examination  will  frequently  show  that 
there  has  been  a  displacement  of  the  country  along  the  dip 
of  the  sandstone  and  limestone  beds,  in  the  strike  of  the  vein 
itself. 

The  question  here  arises,  whether  the  formation  of  the  ore- 
vein  required  the  existence  of  an  open  fissure.  In  the  particu- 
lar case  shown  in  Fig.  28,  the  quantity  of  foreign  material  within 
the  vein  is  insignificant  in  amount ;  the  "  ore  "  being  simply 
altered  rock  in  place.  That  this  rock  became  mineralized  by 
the  penetration  of  metal-bearing  waters  was  probably  due  to 
the  crushing  of  the  granite  by  an  original  slight  faulting  move- 
ment, presenting  facilities  for  circulation  and  consequent  chemi- 
cal interchanges.  Minute  spaces  there  probably  were ;  but 
a  clear  opening,  or  a  slow  crevassing,  such  as  accompanied  the 
formation  of  the  neighboring  dike,  seems  hardly  needed.  The 
ribbon-structure  of  the  Enterprise  section,  in  Fig.  25,  presents 
features  much  more  diflicult  to  explain. 

When  Werner  and  his  school  attributed  the  filling  of  veins  to 
the  agency  of  descending  waters,  the  existence  of  open  fissures 
at  the  time  of  vein-formation  was  conceivable,  because  the 
theory  necessarily  restricted  such  operations  to  the  vicinity  of 
the  surface.  But  the  acceptance  of  ascending  waters  as  the 
main  agents  of  ore-deposition,  and  the  recognition  of  the  condi- 
tions possible  to  the  formation  of  large  masses  of  sulphides,  at 
once  transferred  the  laboratory  of  ore-formation  to  a  deeper 
horizon ;  and  the  suggestion  that  veins  were  filled  by  the  de- 
position of  layers  of  mineral  precipitated  from  waters  passing 
upward  along  fissures  which  were  kept  wide  open  during  such 
time  as  was  required  for  crystalline  growth  to  choke  them  with 
ore,  was  immediately  ridiculed  by  the  miner,  because  his  daily 
experience  taught  him  that  the  vein  once  deprived  of  its  filling 
did  not  remain  open,  but  was  inevitably  closed  by  the  pressure 
of  the  surrounding  rock.  In  many  cases,  in  the  absence  of  arti- 
ficial means  of  support,  his  mine-workings  collapsed,  so  that 
where  there  was  once  a  level  wide  enough  for  a  man  to  walk 


VEIN-WALLS. 


39 


through,  there  came  to  be  only  a  seam  of  mud  enclosed  in 
shattered  rock. 

Despite  the  miner's  objection,  however,  there  is  evidence 
that  fissures  do  sometimes  occur,  which  have  been  sufficiently 
open  to  permit  the  tumbling  in  of  large  pieces  of  rock.  Such 

Fig.  30. 


MAMMOTH  MINE,  ARIZONA. 

an  occurrence  was  observed  in  connection  with  certain  faults 
which  disturb  the  Yirginie  lode  at  Roure,  near  Pontgibaud,  in 
France,*  where,  at  a  depth  of  164  feet  from  the  surface,  a  fault- 
fissure  encloses  a  mass  of  clayey  material  containing  boulders 
of  a  black,  soft,  and  porous  rock,  which  can  be  identified  as 

*  See  Etude  sur  les  yites  metallifZres  de  Pontgibaud  par  M.  Lodin,  Ingenieur-en- 
chef  des  Mines.  Annalesdes  Mines,  April,  1892,  and  "  The  Lodes  of  Pontgibaud," 
by  the  writer,  in  Eng.  and  Min.  Jour.,  August  11  and  18,  1894. 


40  VEIN-WALLS. 

pieces  of  scoriaceous  lava.  No  such  rock  occurred  elsewhere 
underground  ;  and  the  boulders  must  have  been  portions  of  the 
Quarternary  alluvium  which  covered  the  outcrop  of  the  lode, 
and  fell  into  it  at  the  time  of  its  intersection  by  an  open  fissure, 
which  long  post-dated  the  formation  of  the  ore-vein  itself.  The 
mines  are  in  a  district  which  has  frequently  been  subjected  to 
earthquakes,  and  in  the  heart  of  a  region  formerly  the  scene  of 
great  volcanic  activity. 

We  must  be  careful,  however,  to  distinguish  between  the  for- 
mation of  cavities  within  the  zone  of  the  vadose  circulation,  and 
their  existence  in  "  the  deep,"  where  sulphide  ores  have  their 
origin. 

Two  examples  may  be  quoted.  The  first  is  shown  in  Fig. 
29,  sketched  November  25,  1895,  in  the  stopes  above  the  800- 
foot  level  in  the  Indiana  mine,  Gilpin  county,  Colo.  The  lode, 
Avhich  is  the  California  vein,  in  its  extension  westward  from  the 
Hidden  Treasure  mine,  is  about  2  feet  wide.  There  is  no  part- 
ing or  selvage  separating  it  from  the  country.  The  latter  is  a 
quartz-feldspar  rock,  best  described  as  granulite.  Near  the  lode 
it  is  seamed  and  sprinkled  with  pyrite,  and  sufficiently  gold- 
bearing  to  be  sent  to  the  stamp-mill.  The  main  pay-streak  is 
almost  entirely  composed  of  black  zinc-blende  which,  by  candle- 
light underground,  contrasts  strongly  with  its  encasement  of 
light  gray  country.  The  upper  part  of  the  vein,  in  this  particular 
stope,  consists  of  a  breccia  of  zinc-blende,  with  an  occasional 
spattering  of  wall-rock,  the  latter  so  disintegrated  as  to  resemble 
gravel.  At  one  point,  A  B,  there  is  a  shred  of  wall-rock  lying 
across  the  vein.  Lower  down  there  are  a  number  of  cavities 
or  vugs  scattered  among  angular  fragments  of  ore.  It  all  looks 
loose,  like  an  old  stope  filled  with  ore  that  has  been  mined,  but 
the  material  is  hard  and  difficult  to  detach  without  explosives. 
Lower  again,  the  vein  loses  both  its  cavernous  and  its  brecciated 
character,  and  consists  of  a  compact  body  of  blende.  It  may 
be  added  that,  even  where  the  brecciation  is  most  evident,  both 
walls  are  lined  with  a  few  inches  of  ore  unbroken  and  firmly 
attached  to  the  wall-rock  into  which  it  gradates.  The  vugs, 
when  first  found,  were  full  of  gas  (C02,  probably)  and  the 
miners  suffered  from  bad  air  when  working  in  ground  of  this 
character.  The  pieces  of  blende  are  held  together  by  a  siliceous 
cement,  which  also  covers  each  fragment  in  the  form  of  a  gray- 


VEIN-WALLS. 


41 


blue  chalcedonic  coating.  It  is  almost  certain  that  the  cavities 
above  described  contained  water,  previous  to  the  drainage  of 
the  ground  by  the  penetration  of  the  level  underneath. 

Fig    31 


ANDESITE  BRECCIA      fO^|  NEPHELINE  BASALT 


VEIN  MATTER 


THE  MOOSE  VEIN,  CRIPPLE  CREEK,  COLORADO. 

Another  instance  is  suggestive.  In  the  Mammoth  mine, 
Final  county,  Ariz.,  already  described,  the  granite  in  the  east 
cross-cut  at  the  300-foot  level,  north,  has  an  extraordinary  num- 
ber of  fissures  partially  occupied  by  broken  pieces  of  rock,  so 
wedged  in  as  to  leave  open  spaces.  The  pieces  are  not  of  any 
foreign  rock,  but  are  identical  with  the  enclosing  granite.  Fig. 


42  VEIN-WALLS. 

30  is  a  reproduction  from  a  sketch  made  on  the  spot,  March  15, 
1893.  The  elongated  cavities,  such  as  that  illustrated,  were 
found  full  of  water  when  first  reached  by  the  cross-cut ;  but 
they  became  drained  as  the  workings  tapped  them,  and  thereby 
depressed  the  water-level  of  the  mine. 

This  instance  suggests  why  mining  excavations  collapse,  and 
yet  a  natural  cavity  underground  might  remain  open.  The 
former  contains  unconfined  air  only,  while  the  latter  may  be 
filled  with  a  confined  and  practically  incompressible  fluid, 
water. 

It  is  the  usual  experience  in  mining  that  when  the  abandoned 
workings  of  a  mine  are  flooded  they  are  less  likely  to  collapse 
than  when  they  are  dry.  This  is  due  partly  to  the  exclusion  of 
air,  and  partly  to  the  sustaining  power  of  the  water  itself,  as 
suggested  by  Mr.  P.  Argall,  in  the  Eng.  and  Min.  Jour.,  Sep- 
tember 23,  1893,  p.  314. 

The  formation  of  the  hollow  spaces  occasionally  seen  in  veins 
is,  I  believe,  in  most  cases  subsequent  to  the  ore  deposition,  and 
may  therefore  have  taken  place  at  a  time  when  erosion  had 
brought  that  portion  of  the  vein  near  to  the  surface.  The  In- 
diana section,  Fig.  29,  shows  that  the  cavities  have  been  pro- 
duced by  the  shattering  of  a  vein  of  zinc-blende  already  formed. 
The  only  occurrence  of  later  date  is  the  consolidation  of  the 
mass  by  the  agency  of  water  bearing  silica,  unaccompanied,  so 
far  as  can  be  seen,  by  the  deposition  of  any  metallic  minerals. 
In  the  Mammoth  mine,  Fig.  30,  the  blocks  of  rock  wedged 
within  the  cavities  were  coated  with  crystals  of  vanadanite  and 
wulfenite ;  but  there  seems  to  be  no  connection  between  the 
presence  of  these  later  minerals  and  the  formation  of  the  ore- 
bearing  parts  of  the  lode.  They  are  the  result  of  secondary 
processes,  of  which  the  upper  part  of  a  lode  is  the  characteristic 
zone  of  activity. 

The  vein  in  the  railway-cut,  cited  above  as  a  type,  presents  a 
filling  readily  recognizable  as  simply  altered  rock  containing 
only  an  insignificant  percentage  of  material  foreign  to  the  com- 
position of  the  original  granite.  Nor  is  this  an  abnormal  type 
of  vein-structure.  The  rich  gold  mines  on  the  adjacent  hills 
afford  numerous  examples  of  this  very  kind  of  lode-formation. 
(And  incidentally  I  would  say  that  I  know  of  no  mining  dis- 
trict which  illustrates  modern  views  on  ore-deposition  so  clearly 


VEIN-WALLS. 


43 


as  does  Cripple  Creek.)  Of  such  mines  I  would  quote  the 
Independence  vein,  whose  richness  is  such  as  to  cause  its  com- 
mercial value  to  obscure  its  scientific  interest.  It  does  illus- 
trate very  aptly,  however,  this  part  of  our  enquiry,  because  the 
ore  is  so  very  evidently  only  altered  country-rock.  In  1893, 
when  the  workings  had  not  penetrated  far  from  the  surface,  the 
car-loads  of  ore  sent  from  this  mine  to  the  Denver  smelters 
gave  the  impression  that  some  one  had  blundered  and  either 
shipped  waste  from  a  cross-cut  or  else  switched  cars  of  bal- 
last into  the  place  of  loads  of  ore.  One  could  see  that  it  was 
the  normal  Pike's  Peak  granite  with  its  big  pink  feldspar,  but 


Fig.  32 


DRUMLUMMON  MINE,  MONTANA. 

it  required  a  trained  eye  to  note  that  the  mica  had  been  largely 
removed,  leaving  small  iron-stained  patches.  It  was  ore  by 
ourtesy,  because  there  was  enough  gold  present  to  give  it  as 
certain  commercial  value ;  but  to  the  petrographer  it  was  clearly 
granite,  not  much  altered  and  but  slightly  mineralized. 

The  vein  leaves  the  granite  and,  going  northward,  penetrates 
into  andesite  breccia.  Its  character  remains  the  same ;  the  ore 
is  still  altered  country-rock ;  only  now  it  exactly  reproduces  the 
structure  of  its  new  encasement,  and  the  habit  of  the  andesite 
breccia  is  quite  evident,  although  blotches  of  sylvanite  and  fluo- 
rite  may  occasionally  try  to  obscure  it.  The  strike  of  the  vein, 
its  width,  its  richness,  all  appear  unaffected  by  the  passage  from 
one  formation  into  the  other,  while  the  change  in  the  structure 
of  the  ore  is  so  marked  as  to  render  it  easy  for  the  observer  to 
know  what  is  the  enclosing  rock  without  looking  at  the  walls. 


44  VEIN-WALLS. 

In  a  case  such  as  this — and  it  is  not  abnormal — it  is  not  ne- 
cessary to  suppose  the  original  existence  of  an  open  cavernous 
fissure  since  the  material  of  the  vein  is  the  material  of  the  rock 
which  was  there  before  vein  formation  began.  The  vein  follows 
a  line  which  became  a  path  for  metal-bearing  waters.  Minute 
interspaces  there  probably  existed,  such  as  would  be  produced 
by  the  crushing  and  slight  dislocation  of  particles  of  rock  lying 
along  a  line  of  fracture ;  but  a  clear  opening,  a  crevassing,  such 
as  accompanied  the  origination  of  the  dike,  seems  hardly 
needed. 

Occasionally,  it  is  true,  we  do  find  veins  ful]  of  minerals  for- 
eign to  the  encasing  rock  and  so  symmetrically  arranged  in 
bands  having  a  comb  structure  as  to  suggest  to  many  investi- 
gators that  they  were  formed  by  successive  crystalline  growth 
from  the  walls  of  a  vacant  fissure.  Such,  no  doubt,  would  be 
the  interpretation  given  to  the  section  of  vein  illustrated  in  Fig. 
25.  The  reversed  repetition  of  the  quartz,  rhodochrosite  and 
sulphides  is  evident  enough ;  but  the  most  striking  feature  to 
me  is  the  equal  width  of  each  of  the  two  bands  of  the  same 
mineral.  Each  vein  of  mineral  would  seem  to  have  been  frac- 
tured exactly  in  the  middle  previous  to  the  deposition  of  the 
next  succeeding  one. 

This  specimen,  and  numerous  similar  structures  in  the  same 
mine,  indicate  that  the  rhodochrosite  was  the  first  laid  down, 
replacing,  in  part  at  least,  the  crushed  rock  which  encased  an 
original  line  of  fault-fissuring.  Subsequently  another  fracturing 
occurred,  and  this  time  the  line  of  least  resistance  was  the  rho- 
dochrosite itself,  which,  being  homogeneous,  broke  down  its 
center.  The  shattered  carbonate  offered  an  easy  prey  to  the 
sulphide-bearing  waters  which  laid  down  the  blende  and  galena. 
The  presence  of  bits  of  rhodochrosite  within  the  sulphide  band 
indicates  that  the  substitution  was  irregular.  Later,  new  dis- 
turbing forces  were  at  play  and  the  vein  was  fractured  not  only 
along  its  middle,  as  heretofore,  but  also  along  the  lines  of  its 
contact  with  the  encasing  rock.  These  fractures  were  healed 
by  the  deposition  of  quartz,  accompanied  first  by  iron  and  cop- 
per pyrite,  and  then  by  rich  silver-bearing  minerals,  such  as  the 
stephanite.  The  corrosion  of  the  sandstone  on  the  hanging  had 
on  that  side  irregularly  widened  the  vein  so  as  to  give  it  greater 
strength;  therefore  the  next  movement,  the  last,  took  place 


VEIN-WALLS. 


45 


along  the  foot-wall.  This  apparently  resulted  in  nothing  save 
the  crushing  of  some  of  the  encasing  rock  and  the  formation  of 
a  selvage  whose  removal  produced  the  cavity  which  was  so 
striking  a  feature  of  the  stope. 

Another  typical  illustration  of  this  structure  is  presented  by 
the  Amethyst — Last  Chance  vein  (at  Creede,  Colo.)  which  is  cer- 
tainly a  magnificent  example  of  an  ore-break.*  The  country- 
rock,  trachyte,  has  undergone  multiple  fracturing  and  ore  has 

Fig.   33. 


NATURAL  SIZE 


DRUMLUMMON  MINE,  MONTANA. 

been  deposited  along  the  division-planes  so  that  there  are  walls 
ad  libitum.  The  regular  ribbon-structure  produced  by  the  de- 
position of  agatized  quartz  in  a  sheeted  rock  is  very  beautifully 
marked,  and  the  same  process  of  silicifi cation  is  further  evi- 
denced in  those  places  where  the  lode  consists  of  breccia  com- 
posed of  pieces  of  country  covered  by  concentric  layers  of  agate. 
The  lode  itself  is  much  wider  than  the  pay-streak  of  silver-ore, 
^hich  usually  follows  the  foot-wall.  On  the  hanging  the  boun- 
dary between  vein  and  country  is  fairly  discernible ;  on  the 
foot  less  so,  because  for  several  feet  beyond  the  ore  there  is  a 
red  jasper oid  which  gradates  into  country. 

*  At  Red  Mountain,  in  Ouray  county,  Colo.,  it  has  been  the  practice  to  speak 
of  the  veins  (the  Guston,  Yankee  Girl,  and  other  celebrated  lodes)  as  ''ore- 
breaks,"  a  break  in  the  rock  accompanied  by  ore — a  term,  it  seems  to  me,  much 
preferable  to  "fissure  vein." 


46  VEIN-WALLS. 

In  the  Enterprise  example,  Figs.  25  and  26,  each  succeeding 
fracture  occurred  in  the  mineral  deposit  which  had  healed  the 
previous  fracture.  In  other  instances  the  mineral  deposit  ap- 
pears to  have  proved  harder  than  the  encasing  rock  and  the 
second  fracturing  took  place  near  the  original  one,  but  in  the 
soft  rock  rather  than  in  the  hard  vein,  thereby  producing  a 
new  break  parallel  to  the  first  one,  and  close  to  it,  causing  a 
repetition  of  vein-walls  such  as  have  already  been  described  in 
connection  with  the  sections  given  in  Figs.  1,  9,  10,  15  and  21. 
Or  there  may  be  the  production  of  companion-fissures  forming 
contemporaneous  veins,  such  as  are  shown  in  Figs.  13  and  19. 
Finally,  the  companion-fissures  may  be  so  multiplied  as  to  cause 
a  sheeting  of  the  country  and  the  formation  either  of  one  vein 
and  several,  subordinate,  smaller  and  parallel  to  it,  as  in  ~No.  15, 
or  of  a  series  of  ore-streaks  united  by  mineralized  country  so 
as  to  form  one  large  lode,  as  seen  in  Figs.  5,  14,  17  and  31. 

The  evidence  of  a  multiplicity  of  fracturing,  whether  succes- 
sive or  contemporaneous,  is  the  clue,  I  venture  to  believe,  to 
many  of  the  anomalies  of  vein-structure.  No  district  within 
my  knowledge  so  well  illustrates  this  aspect  of  the  inquiry  as 
Colorado's  new  El  Dorado,  Cripple  Creek,  in  El  Paso  county, 
where  gold-veins  occur  as  mineralized  and  enriched  portions  of 
dikes,  phonolite  and  basalt,  traversing  masses  of  andesite  tuff 
and  breccia.  Other  types  are  observable,  but  these  are  to-day 
the  most  characteristic.  The  mineralized  rock  forming  the 
vein  and  that  less  distinctly  gold-bearing  country  which  encloses 
it,  have  been  subjected  to  such  multiple  fissuring  as  to  produce 
a  very  marked  division  of  the  rock  into  parallel  bands  or  sheets 
which  may  be  a  fraction  of  an  inch  apart  or  several  yards. 
This  structure  can  be  seen  no  less  in  hand-specimens  than  in 
blocks  an  acre  big.  The  Moose  vein,  on  Raven  hill,  is  a  fair 
example.  It  is  illustrated  in  Fig.  31,  as  seen  October  27, 1895, 
in  the  back  of  the  sixth  (or  350-foot)  level.  A  is  andesite  tuff 
and  breccia,  B  C  D  is  a  dike  of  dark,  blue-gray  nepheline  basalt, 
subdivided  into  two  barren  parts,  B  and  C,  and  one  ore-bearing 
portion,  D.  Native  gold  and  telluride  compounds  (sylvanite  and 
calaverite)  occur  along  the  seams  in  the  basalt  where  it  is  de- 
composed and  iron-stained.  The  pay-streak  extends  from  E  to 
F,  about  10  inches. 

This  sheeting  or  multiple  fissuring  was  probably  the  result  of 


VEIN-WALLS.  47 

shrinkage  accompanying  the  cooling  of  the  volcanic  rock.  The 
fractures  have  a  contemporaneity  of  origin  quite  distinct  from 
the  successive  ruptures  discussed  in  connection  with  the  ribbon- 
structure  of  the  Enterprise  section.  The  latter  were  marked 
by  the  precipitation  of  diverse  minerals,  while  those  of  a  Cripple 
Creek  vein  are  characterized  by  a  similarity  of  mineral  de- 
position. 

Cases  also  occur  where  there  can  be  discerned  a  combination 
of  both  these  types  of  multiple  lissuring. 

A  line  of  weakness,  or  even  a  region  of  weakness,  once  de- 
veloped in  the  earth's  crust  is  apt  to  continue  to  be  a  line  of 
least  resistance  available  for  future  fracturing.  Even  when  a 
quartz-vein  is  formed  along  a  line  of  rupture,  healing  the  break 
and  strengthening  it  with  a  substance  harder  than  the  rock- 
walls  themselves,  we  may  suppose  that  the  next  break  will  take 
place  along  the  line  of  weakness  presented  by  the  imperfect  co- 
hesion existing  along  the  plane  of  contact  between  the  hard 
quartz  and  the  less  resisting  rock. 

The  gradual  penetration  of  mineral  solutions  into  the  imme- 
diately encasing  country  may  finally  obliberate  the  divisions 
due  to  multiple  assuring.  The  sheets  of  rock  separating  one 
from  the  other  would  be  replaced  by  ore,  and  nothing  might  re- 
main of  the  original  structure  save  faint  partings  in  the  lode, 
such  as  are  less  evident  to  the  eye  than  to  the  hand  of  the 
miner  who  instinctively  uses  them  to  assist  him  in  breaking  ore. 

Thus,  I  believe,  the  collection  of  observations  in  various 
mining  districts  tends  to  the  modification  of  that  idea  of  clean- 
cut  definition  which  accompanied  the  early  ideas  of  vein-struc- 
ture. The  evident  contact  between  two  dissimilar  rocks,  such 
as  is  seen  along  the  walls  of  a  dike,  will  be  often  found  in  veins 
to  be  replaced  by  an  indistinct  gradation  from  mineralized  to 
unmineralized  rock,  originally  the  same  but  now  rendered  un- 
like by  the  selecting  action  of  chemical  solutions. 

We  are  justified,  however,  in  putting  some  limit  to  the  depth 
of  possible  ore-formation,  since  that  formation  is  dependent  on 
the  presence  of  water.  The  record  of  the  largest  number  of 
careful  observations  has  shown  that  as  we  sink  into  the  earth 
the  increment  of  temperature  is  1°  F.  per  each  48  feet  of  de- 
scent. At  this  rate  the  critical  point  of  water  would  be  reached 
at  34,704  feet  or  6J  miles  from  .the  surface.  Where  the  tern- 


48  VEIN-WALLS. 

perature  is  that  of  the  critical  point  (773°  F.)  water  cannot  ex- 
ist as  a  liquid  no  matter  how  great  the  pressure,  but  becomes 
dissociated  into  its  gaseous  elements.  Moreover  we  are  war- 
ranted in  believing  that  the  thermometrical  gradient  becomes 
more  rapid  at  depths  beyond  those  reached  by  human  observa- 
tion because  of  a  decreased  conductivity  in  the  rocks,  or  as  Pro- 
fessor Prestwich,  the  best  authority  on  these  matters,  puts  it  :* 

"  Taking  into  consideration  the  probable  limitation  of  the  percolation  of  water, 
and  the  possible  diminution  of  conductivity  with  increase  of  depth,  if  there  should 
be  any  alteration  in  the  thermometric  gradient,  at  great  depth,  it  will  be  more 
likely  to  be  in  the  direction  influenced  by  these  more  or  less  certain  factors." 

Therefore,  taking  these  conditions  into  consideration,  we  may 
expect  the  circulation  of  water  to  cease  at  20,000  feet  or  there- 
about. But  at  the  maximum  depth  the  maxima  of  temperature 
and  pressure  must  obtain.  It  must  necessarily  be  a  horizon  of 
solution.  Precipitation  would  hardly  begin  until  a  lowering  of 
the  temperature  and  a  lessening  of  pressure  permitted  it.  The 
deposition  of  ore  is  the  direct  result  of  precipitation,  therefore 
actual  ore-formation  is  likely  to  be  limited  to  a  depth  often  of 
15,000  feet. 

It  is  not  difficult  to  surmise  why  clean-cut  fractures  are  not 
necessarily  most  favorable  to  ore  occurrence.  In  the  Drum- 
lummon  mine,  Montana,  the  distribution  of  the  ore  appears  to 
be  connected  with  the  change  in  the  angle  of  intersection  be- 
tween the  course  of  the  veins  and  the  strike  of  the  slate  country. 
Most  of  the  ore-bodies  have  been  found  where  the  course  of  the 
veins  (N.  15°  E.)  cuts  the  slates  at  an  oblique  angle  and  the 
levels  run  out  of  ore  when  their  direction  is  either  at  right  an- 
gles to,  or  conforms  with,  the  strike  of  the  country  (N.  17°  W.). 

Fig.  32  is  a  sketch  made  in  one  of  the  surface-workings  of  that 
mine  which  illustrates  in  miniature  the  fact  above  noted  It  rep- 
resents a  small  quartz-seam  2  inches  wide,  traversing  the  slates, 
whose  structure  is  very  clearly  marked  by  the  color  bands  fol- 
lowing lines  of  original  sedimentation.  Near  the  left  of  the 
sketch  the  quartz  follows  a  joint  and  becomes  narrowed,  while 
where  it  crosses  (along  a  line  of  slight  dislocation)  the  country 
it  has  irregularities  and  bulges  which  answer  to  the  alternating 
slate-bands.  A  rough,  ragged  fracture,  when  continuous,  may 

*  Controverted  Questions  of  Geology,  by  Joseph  Prestwich,  D.C.L.,  F.R.S.,  etc., 
Macmillan,  1895,  p.  247. 


VEIN-WALLS.  49 

be  expected  to  ofter  more  surface  to  solvent  action  and  more, 
but  not  too  many,  obstacles  to  a  rapid  circulation  of  under- 
ground waters.  Its  structure  also  means  more  opposition  to 
the  closing  in  of  the  walls,  because  the  irregular  faces  of  the 
fracture,  when  they  come  together,  leave  openings  which,  if  not 
along  one  section  then  along  another,  have  intercommunica- 
tion, and  so  permit  of  a  passage  which  would  be  badly  im- 
peded, if  not  absolutely  stopped,  by  the  closing  in  of  smooth 
walls. 

Fig.  33  represents,  to  actual  scale,  a  piece  of  slate  enclosing  a 
quartz-vein,  which  came  from  near  the  end  of  the  700-foot  level, 
also  in  the  Drumlummon  mine.  It  so  happens  that  this  is  a 
true  illustration  in  miniature  of  what  the  lode  itself  is  doing  at 
this  point.  The  New  Castletown  lode,  on  which  the  level  is 
driven,  is  at  this  point  cutting  at  right-angles  across  the  bedding 
of  the  slates  and  is  barren  of  ore.  In  the  hand  specimen,  re- 
produced in  the  drawing,  a  quartz-vein,  not  quite  half  an  inch 
wide,  cuts  perpendicularly  across  the  slate  whose  bedding  is 
rendered  beautifully  marked  by  dark  bands.  The  vein  has  a 
uniform  width,  it  has  regular  well-defined  walls  guiltless  of  the 
projections  and  bulges  noticed  in  the  previous  illustration.  It 
may  be  only  a  convenient  coincidence,  but  it  is  a  fact  that  the 
quartz  in  Fig.  25  was  opalescent  and  destitute  of  other  miner- 
als while  that  in  Fig.  24  was  true  ferruginous  vein-quartz. 

Thus  underground  work  bears  daily  testimony  to  the  close 
dependence  of  ore-occurrence  upon  the  geological  structure  of 
the  enclosing  country,  a  relation,  the  importance  of  which  Mr. 
S.  F.  Emmons  has  done  invaluable  service  by  clearly  stating  in 
more  than  one  of  his  contributions  to  the  Transactions.  Want- 
ing a  proper  understanding  of  the  structure  of  the  rock  enca- 
sing his  vein,  the  miner  gropes  but  blindly  in  a  maze  of  tangled 
phenomena  until  the  geologist,  by  their  proper  elucidation, 
gives  him  a  light  which  dissipates  much  of  the  darkness  ob- 
scuring his  progress  underground.  * 


Subject  to  Revision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


TEE  BENDIGO  GOLD-FIELD. 

BY  T.    A.    RICKARD,   ALLEMONT,    ISERE,    FRANCE. 
(Glen  Summit  Meeting,  October,  1891.) 

AMONG  the  names  which  won  a  world-wide  fame  during  the 
golden  age  of  the  early  fifties,  Bendigo  and  Ballarat  were  to  Aus- 
tralia, what  the  Yuba  and  Grass  Valley  were  to  California.  The 
map  of  Victoria  did  not  for  a  long  time  show  the  name  of  old  Ben- 
digo;* for  this  first  and  more  distinctive  name  was  replaced  with 
the  more  English  Sandhurst,  just  as  the  alluvial  diggings  gave  place 
to  quartz  mining.  Towards  the  close  of  last  year,  steps  were  taken 
to  give  back  the  old  name,  as  associated  with  the  early  days  of  rich 
alluvium,  and  more  suggestive  than  the  application  taken  second- 
hand from  an  English  military  academy. 

HISTORY. 

The  first  discovery  of  goldf  in  this  district,  was  made  in  the 
autumn  of  1851  ;  but  there  has  never  been  any  certainty  as  to  the 
day  or  the  man.  At  that  time  the  country  around  Bendigo  Creek  was 
a  part  of  the  Ravenswood  sheep-run,  and  its  resemblance  to  the 
Forest  Creek  district  (now  Castlemaine),  induced  the  first  prospect- 
ing. It  was  late  in  November  when  the  "rush"  broke  out;  the 
shepherds  left  their  flocks ;  the  sylvan  solitudes  were  disturbed  by 

*  The  name  of  Bendigo  is  said  to  have  been  derived  from  a  hut-keeper  on  the 
Ravenswood  sheep-rnn,  who  on  account  of  his  fondness  for  "  fisticuffs  ''  was  nick 
named  Bendigo,  after  the  prize-fighter  of  that  name.  It  is  not  aboriginal,  as  is 
often  supposed,  but  Spanish  ;  and  equivalent  to  our  Benedict.  There  must  always 
be  some  confusion  between  the  two  names  of  Sandhurst  and  Bendigo;  the  town,  and 
with  it  the  gold-field,  having  been  three  times  named.  Several  other  old  familiar 
names  have  been  likewise  unfortunately  replaced  by  second-hand  English  ones;  so 
that  an  old  digger  talks  of  Forest  Creek  when  he  means  the  modern  Castlemaine, 
Mt.  Ida  for  Heathcote,  Growler's  Creek  for  Bright,  etc.  I  shall  use  the  names 
Sandhurst  and  Bendigo  interchangeably. 

t  The  first  discovery  of  gold  in  Australia,  was  made  by  E.  FT.  Hargraves,  February 
12,  1851,  near  Bathurst  in  New  South-Wales.  In  August  of  the  same  year  the  dis- 
covery at  Buninyong,  near  Ballarat,  inaugurated  the  first  of  a  series  of  rushes  to 
the  Victoria  gold-fields. 

1 


2  THE   BENDIGO   GOLD-FIELD. 

the  voices  of  the  first  "diggers  ;"  the  green  glades  of  Bendigo  .Creek 
were  ruthlessly  uptorn  by  pick  and  spade ;  and  the  busy  energetic 
life  of  a  young  and  thriving  mining  camp  replaced  the  sleepy  idle 
routine  of  an  out-of-the  way  sheep-station. 

Since  that  date  the  gold-field  has  yielded  over  fifteen  million 
ounces  of  the  precious  metal,  valued  at  more  than  sixty  millions 
sterling.  Like  most  mining  districts,  it  has  passed  through  days  of 
severe  depression  and  extreme  inflation.  Until  1854  the  alluvium 
only  was  worked.  The  pan  and  the  cradle  early  gave  way  to  the 
paddling-tub,  a  machine  more  suited  to  the  clayey  character  of  the 
wash.  By  reason  of  the  limited  supply  of  water,  the  long  torn  was 
never  very  widely  used.  The  highest  output  on  record  was  reached 
in  1853,  when  661,729  ounces,  valued  at  £2,646,800,  were  obtained 
from  the  alluvium  only.  Long  before  the  diggers  were  aware  of  the 
real  value  of  gold-quartz,  they  used  to  amuse  themselves  by  break- 
ing off  specimens  from  the  outcrops  for  decorative  purposes.*  Dia- 
mond Hill  owes  its  name  to  the  beautiful  specimens  which  its  surface 
yielded  in  the*  early  days.  Vein-mining  or  "  quartz-reefing"  had 
its  inception  with  the  discoveries  made  by  Ballestedt  on  Victoria 
Hill,  which  has  now  been  pierced  for  a  depth  of  over  half  a  mile, 
and  is  honeycombed  with  deep  workings.  From  1854  to  1862,  the 
quartz-mining  industry  had  a  chequered  career;  as  will  be  readily 
understood  when  the  peculiar  character  of  the  ore-deposits  has  been 
passed  in  review.  In  1859  the  first  regular  registration  of  a  quartz- 
minef  took  place.  About  this  period  the  shallow  alluvial  deposits 
became  exhausted  and,  in  the  absence  of  deeper  channels,  the  whole 
energy  of  a  very  enterprising  community  was  concentrated  upon  the 
exploitation  of  the  quartz-lodes.  In  1862  the  first  limited-liability 
company  was  brought  out;  and  in  the  immediately  succeeding  years 
the  steady  development  of  the  field  and  the  increasing  knowledge  of 
the  lode-structure  were  accompanied  by  an  increasing  gold-output, 
which  rose  in  1870  to  241,380  ounces.  The  formation  of  numerous 
companies  which  marked  the  early  seventies,  introduced  fresh  capi- 
tal into  the  district,  and  thus  led  to  great  increase  in  the  work  done 
in  the  mines,  the  output  from  which  averaged  at  this  time  over 
300,000  ounces  per  annum.  But  company-promotion  soon  devel- 

*  So  ignorant,  it  is  reported,  were  the  pioneers  of  gold-mining  in  those  days,  that 
many  immigrants  went  to  the  rushes  or  mining  stampedes  with  the  idea  that  "  gold 
in  quartz"  meant  gold  in  quarts  or  pailfuls! 

f  This  was  the  Johnson's  gold-mine,  which  is  still  a  rich  producer,  having 
headed  the  dividend  list  for  1890  with  £30,800. 


THE   BEXDIGO   GOLD-FIELD. 


oped  into  a  mania  which  rapidly  did  its  evil  work.  Paper  mining 
replaced  honest  work,  as  it  has  done  in  many  another  mining  district 
before  and  since.  A  reaction  set  in ;  the  gold-field  saw  its  darkest 
days;  and  a  collapse  took  place  which  ended  the  wild  speculation  in 
bogus  companies  and  marked  the  commencement  of  a  new  era  of 
steady  progress.  The  opening  up  of  deeper  ground  and  a  renewal  of 


Fig. 


Lradley  $  Poates  Sngrs.  A'.  Y. 


SCALE.    t«50    MH.ES 


:C*j  VOLGA  NIC 


HJQRANITE 


GEOLOGICAL  SKETCH    MAP 

OF  A    PORTION    OF 

VICTORIA. 


rich  discoveries,  brought  about  a  revival  in  the  first  years  of  the  last 
decade,  which,  accompanied  as  it  has  been  by  great  enterprise,  and 
the  intelligent  development  of  the  mines  with  a  more  accurate 
knowledge  of  their  ore-deposits,  has  enabled  the  Bendigo  gold- 
field  to  hold  the  first  place  among  the  quartz-mining  districts  of 
Australasia,  and  to  make  its  record  unique  in  the  statistics  of  this 
industry. 


4  THE    BENDIGO    GOLD-FIELD. 

To  the  members  of  the  Institute,  probably  few  mining  districts  are 
less  known,  considering  their  importance,  than  those  of  the  colony 
of  Victoria.  The  steamship,  the  railway,  and  the  telegraph,  have 
linked  together  the  most  distant  mining  centers,  Broken  Hill  and 
Virginia  City,  Johannesburg  and  Grass  Valley;  but  the  older  gold-, 
fields  of  Australia  have  received  but  a  superficial  and  passing  notice 
from  the  pens  of  standard  writers.  More  particularly  is  this  true  of 
Sandhurst  or  Bendigo,*  which  shares  with  Ballarat  the  first  rank 
among  the  Australian  localities  of  quartz-mining.  This  mining 
center  and  its  peculiar  ore-deposits  it  is  my  purpose  to  describe, 
from  the  notes  of  a  recent  examination.  The  time — three  mouthsf — 
was  insufficient  to  enable  me  to  give  to  the  field  the  extended  study 
which  it  invited;  and  I  would  leave  the  subject  to  better  hands,  did 
I  not  believe  that  the  objects  of  our  Institute  are  best  carried  out, 
when  its  members  place  on  record  the  different  facts  observed  in 
different  countries,  in  order  that  a  mass  of  observations  may  ulti- 
mately be  accumulated,  which  those  best  qualified  may  combine  and 
discuss. 

GENERAL  DESCRIPTION. 

At  the  outset  a  general  description  of  the  appearance  of  the  gold- 
field  may  be  of  interest.  A  very  good  view  can  be  obtained  from 
the  upper  platform  of  the  Old  Chum  poppet-heads,!  on  Victoria 
hill.  The  air  is  usually  clear,  and  from  this  point  of  vantage  one 
can  see  a  long  way.  The  district  lies  among  a  series  of  undulations 
which  rise  above  the  tame  level  of  the  surrounding  plains.  The 
even  line  of  the  latter  is  further  broken  by  several  hills,  marking  the 
granite  bosses  which  penetrate  the  overlying  slates  and  sandstones. 
To  the  north,  poppet-heads  and  tall  red  brick  chimneys  in  long  suc- 
cession indicate  the  various  great  lodes  or  "  lines  of  reef,"§  stretching 
out  to  Eaglehawk,  four  miles  away,  while  out  in  the  distance  be- 

*  Only  the  more  recent  works  on  gold-deposits  contain  any  references,  and  these 
are  almost  invariably  inaccurate  and  misleading  in  their  descriptions  of  the  mode 
of  occurrence  of  the  quartz.  Lock's  Gold  which  is,  generally  speaking,  a  very 
complete  compilation  on  the  subject,  contains  only  one  reference  to  Sandhurst, 
comprised  within  a  paragraph  of  a  dozen  lines. 

f  April,  September,  and  part  of  October,  1890,  also  a  part  of  February,  1891. 
•     %  "  Poppet  heads"  is  the  English  and  colonial  equivalent  for  the  Western  "gal- 
las  "  or  gallow's  frame.     "  Three  legs  "  and  "  heapsteads  "  are  the  names  used  in  the 
north  of  England. 

\  A  "  line  of  reef"  is  a  reef  or  lode  taken  as  a  whole.  The  mines  of  Amador, 
Calaveras,  and  Tuolumne  counties  would  be  said  to  be  on  "  the  same  line  of  reef," 
viz.,  "the  Mother-lode"  of  California. 


THE    BEXDIGO   GOLD-FIELD. 


yond  is  the  dark  blue  sea  of  the  trackless  bush,*  broken  in  front  by 
the  hills  at  Kerang  and  to  the  right  by  the  promontory  of  the  White 
hills,t  a  name  familiar  to  every  Australian  digger.  White  hills 
they  are  no  longer,  for  the  "cement"  which  covered  the  rich  allu- 
vium has  become  oxidized,  and  patches  of  red  gravel-heaps  have 
replaced  what  was  once  glistening  white.  Between  these  and  the 
spectator  lies  the  modern  city  of  Sandhurst,  its  well  laid  out  streets 
lined  with  the  English  trees  which  have  replaced  the  gums  that 
once  covered  the  site.  A  wavering,  blue,  irregular  line  marks  Ben- 
digo  creek,  once  flowing  through  the  forest  glades,  but  now  mean- 
dering past  tailing-heaps  and  back  yards.  Out  beyond  the  town  we 


Fig.  2. 


hVy.V.V.-.ISANDSTONE     |^=g=j  SLATE 

SADDLE. 


QUARTZ. 


can  dimly  see  Mt.  Ida,  where  Heathcote  lies.  Southward  the  suc- 
cession of  poppet-heads  marks  the  auriferous  belt.  The  engine- 
houses  of  the  South  Bellevue  and  Eureka  Extended  mines  indicate 
the  Xew  Chum  reef,  on  which  there  is  operated  to-day  perhaps  the 
greatest  series  of  deep  gold-quartz  mines  which  the  world  has  yet 
seen.  A  new  church  rises  above  Golden  Square,  the  scene  of  some 
of  the  first  and  richest  of  the  alluvial  diggings.  The  view  is  further 
diversified  by  gray  heaps  of  tailings,  bluish  piles  of  waste  rock,  gar- 

*  The  forest  of  Eucalyptus,  which  at  one  lime  covered  the  whole  of  the  habitable 
portion  of  the  Australian  continent. 

f  The  White  Hills  of  Bendigo  and  the  Black  Hill  at  Ballarat  are  in  the  history 
of  Australian  gold  discovery  what  Mokelurane  Hill  in  old  Calaveras,  and  Table 
Mountain  in  Tuolumne  were  to  California,  or  what  Ruby  Hill  at  Eureka,  and  Mt. 
Davidson  at  the  Comstock  were  to  Xevada. 


6  THE    BEXDIGO   GOLD-FIELD. 

dens  and  houses,  among  which  is  seen  the  sinuous  curve  of  the  rail- 
way along  which  the  Melbourne  express  is  now  coming.  Further 
south,  in  the  distance,  are  the  granitic  slopes  of  Mt.  Alexander,  be- 
yond which  lies  Castlemaine.  To  the  west,  clouds  of  sulphurous 
smoke  indicate  the  various  pyrites-works,  and  a  black  line  against 
the  blue  sky  marks  the  water  supply  flume,  while  immediately  be- 
low us  are  the  gardens  and  house  of  one  of  the  mine-owners,*  an  oasis 
of  pleasant  green  among  the  stern  practical  surroundings  of  mines 
and  mills. 

Sandhurst  or  Bendigo  has  a  population  of  over  30,000  inhabitants, 
several  fine  public  buildings,  and  some  very  beautiful  public  gar- 
dens. It  is  connected  with  Melbourne,  the  chief  port  and  metropo- 
lis of  Victoria,  by  a  double-track  railway  101  miles  long,  constructed 
at  a  cost  of  £18,000  per  mile. 

STATISTICS  OF  PRODUCTION. 

A  few  figures,  taken  from  the  annual  report  of  the  Secretary  for 
Mines,  will  indicate  the  size  and  importance  of  the  Bendigo  gold- 
field.  During  the  past  two  years  the  gold-production  of  the  three 
leading  Australian  colonies  has  been  as  follows: 


Victoria,  1889,      . 
1890,       . 

New  South  Wales,  1889 
"  "  1890 

Queensland,  1889, 
"  1890, 

The  year  1889  was  the  first  in  which  Victoria  did  not  lead  the 
colonies,  being  surpassed  by  Queensland  through  the  Mt.  Morgan 
mine,  whose  output  alone  was  over  300,000  ounces.  The  marked 
decrease  in  the  yield  of  Queensland  for  1890  is  similarly  due  to  a 
decline  in  the  output  from  Mt.  Morgan.  The  explanation  of  the 
Queensland  average  of  £288  per  miner,  in  1889,  is  explained  by  the 
fact  that  the  most  of  the  value  of  the  product  of  Mt.  Morgan  in  that 
year  found  its  way  into  the  pockets  of  half  a  dozen  men. 

The  yield  of  588,560  ounces  (1890)  is  the  lowest  on  record  in  the 
history  of  gold-mining  in  Victoria.  There  has  been  a  gradual  de- 
crease during  the  past  decade,  mainly  due  to  the  exhaustion  of  the 
more  readily  accessible  alluvial  deposits. 


Ounces. 

Value. 

No.  of 
miners. 

Average  per 
miner. 

£. 

£. 

s. 

d. 

614,838 

2,459,352 

24,323 

101 

2 

2 

588,560 

2,354,240 

23,833 

98 

15 

7 

119,758 

434,070 

10,192 

42 

11 

9 

127,460 

459,086 

12,182 

37 

13 

8 

737,822 

2,582,377 

8,955 

288 

7 

5 

600,000 

2.100.000 

Fortuna  Villa,  the  residence  of  M.  George  Lansell. 


THE   BEXDIGO   GOLD-FIELD.  7 

From  1851  to  the  end  of  1890  the  yield  of  gold  from  Victoria 
amounted  to  56,870,574  ounces,  valued  at  £227,482,296,  an  average 
per  year  of  1,452,761  ounces,  the  highest  for  any  single  year  being 
3,053r744  ounces,  in  1856.  Of  this  total,  Bendigo  has  contributed 
11,168,414  ounces,  valued  at  £44,673,656.  In  addition,  it  is  esti- 
mated that  the  gold  taken  away  privately  to  Melbourne  and  the 
neighboring  colonies,  and  not  included  in  the  government  returns 
for  the  district,  will  amount  to  4,000,000  ounces,  which  would  give 
a  round  total  of  over  15,000,000  ounces,  valued  at  over  £60,000,000 
sterling. 

Victoria  is  divided  into  seven    mining   districts,   of  whfch  the 


*i$m 


.yV--.X--.lSANDSTONE     |=gg^|8LATE  frW<i  QUARTZ 

FALSE  SADDLE. 

most  important  are  Ballarat  and  Bendigo,  the  former  being  the  chief 
alluvial  center,  while  the  latter  leads  the  quartz-mining  districts. 
The  total  area  of  the  Victoria  gold-fields,  86,760  square  miles,  is 
worked  and  prospected  by  a  force  of  23,833  miners ;  and  the  propor- 
tion belonging  to  the  two  principal  gold-fields  is  as  follows : 

Area  in 
sq.  miles.         Miners. 

Bendigo,         .        ...        *        .         .         .     5,870  4,420 

Ballarat, 5,180  6,249 

While  the  mining  operations  in  the  Ballarat  district  are  distributed 
over  an  actual  area  of  40  square  miles,  and  the  boundaries  include 
such  important  centers  as  Clunes  and  Creswick,  those  of  the  Ben- 


8  THE   BENDIGO   GOLD-FIELD. 

digo  district  are  practically  concentrated  upon  an  area  of  21  square 
miles  within  the  adjacent  townships  of  Eaglehawk  and  Sandhurst. 
During  the  past  2  years  the  yield  of  gold  has  been : 

Alluvial.  Quartz.  Total.         * 

Oz.      dwts.  grs.          Oz.      dwts.  grs.         Oz.       dvvts.  grs. 

Bendigo,  1889,      6,973     12     10  134,547      8     21  141,521       1       7 

"         1890,      3,293      3     18  134,671     10     11  137,964     14      5 

Ballarat,  1889,    98,342       6     13  117,321     18       0  215,664      4     13 

"         1890,    92,836      2     10  117,597      0      8  210,433      2    18 

It  is  seen  that,  while  Ballarat  is  the  leading  alluvial  district,  it 
produces  also  a  large  proportion  of  gold  from  quartz,*  while  at  Ben- 
digo, on  the  other  hand,  the  alluvium  is  relatively  important.  The 
figures  just  given  bear  out  the  statement  of  the  Secretary  for  Mines 
that  the  diminution  of  the  gold-yield  is  chiefly  in  that  from  the  allu- 
vial mines.  In  both  the  leading  centers  the  yield  from  quartz  has 
slightly  increased,  while  that  from  alluvium  has  considerably  dimin- 
ished. The  average  yield  of  the  quartz  per  ton  of  ore  crushed,  dur- 
ing the  past  year,  was  as  follows  : 

dAvts.  grs. 

Victoria  (average  of  the  seven  districts),       „        ••..•'       .9       4 
Bendigo,  .        .   .     ,        .        ,        .        ,        .        .        •        .     9      5 

Ballarat,.        ./I        .  ;  U  •  : '.        .     ;->       :. .      .        .    7     21 

The  average  yield  from  pyrites  and  blanketings  was: 

,                                        Total  treated.  Total  yield.                     Average. 

Tons.     cwt.  Oz.     dwts.  grs.  Oz.  dwts.  grs. 

Bendigo,         .        .     1,766     10  3,901     16     12  244 

Ballarat,         ;        .    2,148       0  5,196     19      7  289 

The  highest  and  lowest  prices  paid  for  the  gold  per  oz.  were,  at 
Bendigo,  £3  17s.  and  £3  19s.,  and  at  Ballarat,  £3  17s.  6d.  and  £4  3s. 

While  in  the  colony  as  a  whole  the  number  of  miners  is  pretty 
equally  distributed  between  alluvial  and  quartz  mines — 11,470  in 
the  former  to  12,363  in  the  latter — there  is,  in  the  two  leading  dis- 
tricts, a  greater  disproportion  ;  Bendigo  having  949  alluvial  and 
3375  quartz-miners,  while  Ballarat  has  2440  alluvial  and  3677 
quartz-miners.  At  Sandhurst  there  are  270  Chinamen,  nearly  all 
engaged  in  surface-washing,  while  at  Ballarat  there  are  736  Mon- 
golians to  5508  Europeans. 

*  At  Ballarat,  as  the  deep  leads  (alluvial)  were  becoming  worked  out,  the  crop- 
pings  of  the  quartz-veins  were  found  in  the  bed-rock  of  the  alluvium.  Several 
claims  which  have  been  rich  in  alluvium  are  now  good  quartz-mines. 


THE    BEXDIGO   GOLD-FIELD. 


9 


The  Bendigo  gold-field  includes  several  scattered  subdivisions; 
but  it  consists  practically  of  Eaglehawk  and  Sandhurst  (or  Bendigo), 
two  distinct  municipalities,  forming  one  long  straggling  township, 
somewhat  after  the  manner*  of  Gold  Hill  and  Virginia  City,  or 
Black  hawk  and  Central  City. 

In  1890  the  machinery  employed  in  quartz-mining  was  thus  dis- 
tributed : 


Sandhurst, 
Eaglehawk, 


Steam-  Machine  Concen-  Arras- 
engines.  Stamps.      drills.  trators.  tras. 

.     175            625            70  65  25 

105           501           40  40  6 


For  the  Bendigo  gold-field  as  a  whole,  the  numbers  are  as  fol- 


Fig.  4. 

GARDEN  GULLY  LINE 


IDEAL  SECTION. 

SHOWING  THE  MAIN   LINES  OF  REEF. 


Bradley  &  P^.ttt 


Engrt.  S.  F. 


lows:  Steam  engines,  316;  aggregate  nominal,  H.P.  6873;  stamp- 
heads,  1328;  whims,  76;  whips,  127;  machine-drills,  128;  con- 
centrators, 105;  arrastras,  82.  The  total  value  is  estimated  at 
£478,611.  Considering  the  size  and  yield  of  the  district,  the  value 
of  the  machinery  is  small  indeed,  when  compared  to  that  of  a 
Western  American  mining-camp,  with  its  much  larger  and  more 
costly  hoisting-engines,  mills,  etc. 

*  But  the  mining  townships  of  Victoria  are  very  different  from  those  of  the 
great  West.  Ballarat,  Sandhurst,  Chines,  and  Creswick  are  pretty  towns,  situated 
in  rich  agricultural  districts,  and  presenting  none  of  that  bare  ruggedness  which  is 
characteristic  of  most  mining  camps  of  Colorado,  Nevada,  and  California. 


10  THE   BENDIGO    GOLD-FIELD. 

The  quantity  and  cost  of  the  timber  consumed  for  mining  pur- 
poses during  the  year  were  as  follows  : 

Firewood,* .  146,628  tons. 

Props  and  cap-pieces, 105,533  pieces. 

Laths  and  slabs,          .        .        .        .        .        .        .      80,820      " 

Sawn  timber,      .     ".  V1.        .'    ",    ''.•'.'     .  821,232  feet. 

The  value  of  this  is  set  down  at  £63,856  6s.  6d. 

Mining  is  carried  on  for  the  most  part  by  companies,  whose  share 
capital  is  invariably  small  and  their  reserve  capital  usually  nil. 
The  tribute-system  is  largely  in  use,  and,  here  as  elsewhere,  often 
leads  to  the  discovery  of  valuable  ore-bodies.  There  are  few  private 
mines,  the  most  important  of  which  belong  to  Mr.  Lansell,  a  mine- 
owner,  the  record  of  whose  enterprise  forms  an  important  part  of 
the  history  of  the  field.  A  few  small  parties  of  miners,  less  numer- 
ous than  the  future  prosperity  of  the  district  requires,  are  engaged 
in  prospecting  new  grounds. 

Operations  are  distributed  among  eleven  approximately  parallel 
formations  or  "  lines  of  reef,"  of  which  by  far  the  most  important 
are  the  New  Churn, f  the  Garden  Gully  and  the  Hustlers.  At 
present  the  greatest  activity  prevails  along  the  first-named  which 
has  also  been  the  most  continuously  profitable  of  the  series.  A 
notion  of  the  extent  of  the  field  and  its  worthiness  to  -rank  among 
the  greatest  of  modern  mining  centers  may  be  obtained  from  the 
following  statements.  The  New  Chum  lode  has  been  worked  from 
Axe  Creek  to  the  Franklin  mine  in  Sailors'  Gully,  a  distance  of 
fourteen  miles.  The  Garden  Gully  has  been  followed  from  the 
Suffolk  Tribute  and  the  Moon,  beyond  Eaglehawk,  to  the  Great 
Southern  Extended,  beyond  Bendigo  Creek,  a  distance  of  7  miles. 
The  third  great  lode,  the  Hustlers,  has  been  tapped  at  the  Fortuna 
Hustlers  in  the  city  of  Sandhurst,  and  from  there  has  been  worked 
as  far  as  the  King  of  Prussia,  in  Opossum  Gully,  which  is  5  miles 
away.  So  much  for  the  extent  of  working  along  the  strike.  Down- 
wards, the  New  Chum  has  been  followed  for  a  vertical  depth  of  over 
half  a  mile  (2641  feet),  the  Garden  Gully  for  over  2300  feet  and  the 
Hustlers  2000  feet.  There  are  in  Sandhurst  18  shafts  exceeding  in 
depth  2000  feet.  Several  of  these  are  still  going  down  ;  and  of  the 

*  Fifty  feet  of  firewood  equal  one  ton  of  2240  pounds.  Laths  and  slabs  are  the 
same  as  what  the  American  calls  "  lagging." 

f  "  New  Chum "  is  the  colonial  equivalent  of  the  Western  "  tenderfoot,"  i.e.,  a 
fresh  arrival  in  the  countrv. 


THE   BEXDIGO   GOLD-FIELD. 


11 


20  companies  among  which  these  18  shafts  are  distributed,  3  are  in 
rich  ore,  7  are  breaking  pay-ore,  9  are  prospecting  and  1  is  idle. 

Though  the  output  has  suffered  during  the  past  two  years  by 
reason  of  the  greater  attractions  presented  by  gambling  in  silver 
shares  at  Broken  Hill,  Sandhurst  contained  during  the  past  year  28 
dividend-paying  companies  which  produced  101,879  ounces  10  dwts. 
(not  including  7  tribute  parties  which  were  dividend  paying), 
enabling  the  payment  of  £149,381  17s.  in  dividends.  The  work 
of  the  past  year  has  shown  an  improvement  as  indicated  by  the  fol- 
lowing comparison.  In  1889  the  calls  amounted  to  £137,489,  the 


Fig.  5. 


dividends  to  £118,473,  a  balance  on  the  wrong  side  of  £19,016.  lu 
1880  the  calls  were  diminished  to  £111,142,  while  the  dividends 
increased  to  £149,38,1,  leaving  a  profit  of  £38,239.  During  the 
last  14  years  the  dividends  have  exceeded  the  calls  by  £1,101, 836,  the 
year  1889  being  the  only  unprofitable  period.  Roughly  speaking, 
during  1890  each  ounce  of  gold  was  obtained  at  a  cost  of  £2  10s.  Sd.t 
leaving  £1  9s.  4d  as  profit  for  the  shareholders. 

Out  of  the  28  companies  which  appeared  on  the  dividend-list  at 
the  beginning  of  1891,  the  20  whose  records  are  obtainable  show 
that  only  four  have  failed  to  pay  back  the  capital  expended 
upon  them,  and  of  these  four,  one  is  not  yet  a  year  old.  The 


12 


THE    BEKDIGO    GOLD-FIELD. 


average  total  dividends  of  each  of  these  20  properties*  amounts 
to  £81,947,  the  average  nominal  capital  of  each  is  £49,742, 
while  the  average  paid  up  capital  is  only  £34,167.  It  is  seen,  there- 
fore, that  these  20  companies  have  returned  in  dividends  nearly 
twice  the  amount  of  capital  called  up  for  their  equipment  and  de- 
velopment. Further,  it  should  be  stated  that  the  number  under 
consideration  does  not  include  several  of  the  minesf  which  have  the 


*  The  following  list  gives  the  detailed  figures  of  the  twenty  companies  which 
were  dividend-paying  at  the  beginning  of  this  year  (1891).      The  results  are  given 

up  to  the  end  of  1890: 

Nominal 

Paid  up 

Company. 

capital. 

capital. 

Dividends. 

£. 

£. 

£. 

Catherine  Eeef  United,  . 

135,200 

82,810 

50,755 

Fortuna  Hustlers,   . 

14,000 

3,500 

2,800 

Gt.  Ex.  Hustlers, 

68,000 

62,050 

419,200 

Hercules  and  Energetic,          . 

60,000 

8,250 

74,625 

Johnson's  Reef,       .    ,    .        . 

78,000 

72,100 

223,950 

Lazarus  New  Chum,        .        . 

67,500 

63,187 

67,500 

Lazarus  No.  1,         .         . 

67,500 

63,950 

95,062 

Lady  Barkly,  .        .        .        . 

24,000 

17,400 

58,315 

New  Chum  Con,     .        V 

42,000 

18,200 

132,300 

New  Chum  Railway,       .         . 

36,890 

28,589 

52,078 

New  Chum  United,          .        , 

14,750 

8,850 

66,375 

North  Old  Chum,    . 

54,000 

33,075 

86,495 

Rose  of  Denmark,    .         .        . 

24,000 

4,800 

63,600 

45,000 

27,750 

15,750 

Shenandoah,    .        ,        ,        . 

96,000 

33,600 

59,600 

South  New  Chum,  .        .        . 

32,000 

21,735 

800 

Specimen  Hill  United,    . 

20,000 

12,000 

23,500 

United  Hustlers  and  Redan,  . 

48,000 

19,200 

114,000 

United  Devonshire, 

28,000 

9,800 

21,700 

Young  Chum,          . 

40,000 

32,500 

10,550 

Totals,    .        .        ." 

994,840 

623,346 

1,638,955 

Averages,       .        « 

49,742 

31,167 

81,947 

f  The  greatest  producers  have  been  the  following  mines : 

Called  up 

Name.  qp,piial.  Dividends. 

£.  £. 

Garden  Gully  United 21,642  667,796 

Gt.  Extended  Hustlers, 62,050  419,200 

Johnson's  Reef, 72,100  223,950 

Gt.  Hustler's  Tribute, 61,200  620,200 

North  Johnson's,       ....'..     31,850  148,625 

United  Devonshire 8,244  224,000 

New  Chum  Con., 18,200  132,300 

There  are  many  others,  the  totals  of  whose  dividends  is  more  than  £100,000. 


THE    BEXDIGO   GOLD-FIELD. 


13 


greatest  records,  but  have  temporarily  dropped  out  of  the  divi- 
dend-list. 

The  instances  of  individual  productiveness  here  have  been  sur- 
passed in  other  parts  of  the  world  ;  but  it  is  doubtful  whether  in  the 
history  of  gold-mining  there  can  be  shown  a  better  record  in  the 
proportion  of  dividends  paid  to  capital  expended.  The  product  of 
the  mines  from  tribute-parties  is  not  included  in  the  above  list  unless 
especially  mentioned.  It  is  a  matter  of  record,  for  instance,  that, 
including  the  product  of  the  tributers,  the  Garden  Gully  United  has 
yielded  over  £1,000,000.  The  Kentish  mine  of  the  late  I.  B. 
Watson  is  said  to  have  yielded  over  £2,500,000;  and  another 
private  mine,  G.  Lansell's  "ISO/7  has  given  magnificent  profits  to 
its  owner,  as  have  also  several  tribute-workings,  the  records  of  which 
are  not  accessible  now. 

To  the  Australian  tBe  name  of  Sandhurst  is  always  associated  with 


Fig.  6. 


INVERTED  SADDLES. 

the  "saddle-reefs."  It  was  the  frequent  mention  of  these  which  led 
me  to  visit  the  mines  ;  and  it  is  the  peculiar  interest  which  they  must 
have  for  all  geologists  and  mining  engineers  which  has  induced  the 
publication  of  these  notes.  Before  discussing,  however,  these  and 
other  matters  of  detail,  a  general  account  of  the  geology  of  the 
district  should  be  given. 

GEOLOGY. 

As  will  be  seen  by  a  reference  to  the  map*  of  Victoria  (Fig.  1)? 
the  gold-field  is  situated  near  the  northern  edges  of  the  exposure  of 
the  Lower  Silurian,  which,  a  short  distance  further  north,  is  over- 
lain by  Pliocene  shales.  The  boss  of  granite  at  Mt.  Hope  suggests 

*  The  geological  map  of  a  portion  of  Victoria  which  accompanies  this  paper, 
was  copied  by  me  from  the  geological  sketch-map  in  The  Geology  and  Physical 
Geography  of  Victoria,  by  R,  A.  F.  Murray,  the  geologist  of  the  Victorian  govern- 
ment. 


14  THE    BENDIGO    GOLD-FIELD. 

the  deeper  masses  of  crystalline  rocks  which  also  form  the  M£  Alex- 
ander ranges,  dividing  the  Sandhurst  and  Castlemaine  gold-fields. 
The  gold-mining  districts  of  Victoria  are  almost  entirely  confined  to 
beds  of  Upper  and  Lower  Silurian  age,  of  which  Mr.  Murray  says  :* 
"As  surface  or  underlying  rocks,  they  occupy  the  greater  part  of 
Victoria  from  the  sea-coast  to  elevations  exceeding  6000  feet." 
They  form  the  bed-rock  of  the  alluvium  the  yield  of  which  aston- 
ished the  world  in  1851,  and  the  country-rock  of  the  quartz-lodes 
from  which  that  alluvial  gold  was  derived.  Selwynf  computed  their 
total  thickness  to  be  not  less  than  35,000  feet.  While  the  line  of 
division  between  the  two  horizons  has  not  been  found,  certain  differ- 
ences in  lithological  character  and  fossil  remains  have  led  the  Vic- 
torian Geological  Survey  to  refer  to  the  Upper  Silurian  that  portion 
of  the  Silurian  rocks  lying  east  of  a  line  drawn  from  Melbourne  to 
Heathcote,  while  the  Silurian  west  of  that  line*  is  regarded  as  Lower. 
It  is  in  the  lower  horizon,  which,  according  to  Professor  McCoy,  cor- 
responds to  the  Llandeilo  Flags  and  Bala  rocks  of  Wales,  that  the 
auriferous  deposits  of  Ballarat,  Castlemaine,  and  SandhurstJ  occur. 
In  the  upper  are  the  Ovens  district,  the  Buckland  and  Harriet- 
ville.  Again,  to  the  latter  belong  the  picturesque  alpine  districts, 
and  to  the  former,  the  extensive  plains  diversified  by  low  rounded 
hills. 

While  there  is  a  general  similiarity  in  the  mode  of  occurrence  of 
the  gold,  there  are  also  some  interesting  differences  in  the  habits  of 
the  quartz-lodes  in  the  two  horizons.  The  auriferous  deposits  are 
found  traversing  certain  defined  belts,  which  have  a  general  strike 
20°  to  30°  west  of  north.  These  parallel  belts  contain  veins  of 
quartz  which  conform  to  the  general  strike,  and  which,  like  the  belts 
themselves,  are  separated  by  barren  portions  of  country.  My  ob- 
servations lead  me  to  believe  that  the  gold-veins  of  the  Lower  Si- 
lurian are  more  often  conformable  to  the  stratification,  while  those 
of  the  Upper  are  more  frequently  true  fissures,  traversing  the  country 
at  an  angle  to  the  bedding.  R.  A.  F.  ^Murray,  the  government 
geologist,  has  noted  that  while  the  quartz-reefs  in  the  Upper  Silurian 

*  Page  33  of  the  book  mentioned  in  the  preceding  note. 

f  A.  R.  C.  Selwyn,  formerly  head  of  the  Geological  Survey  of  Victoria,  and  now 
occupying  a  similar  position  under  the  Canadiari  government. 

J  The  fossils  most  common  in  the  rocks  at  Sandhurst,  are  graptolites,  particularly 
stellatus,  extensus  and  tripedes,  together  with  Sertul'iria  mayna  and  vergata,  Didymo- 
grapsus,  fruticosus  and  Phyllograpsus  folium.  In  the  weathered  slate-beds  they  are 
easily  found,  but  underground,  the  dark  color  of  the  rock,  and  the  development  of 
fine  cleavage  renders  them  difficult  of  recognition. 


THE   BEXDIGO   GOLD-FIELD. 


15 


16  THE    BENDIGO   GOLD-FIELD. 

may  be  fewer  in  number  and  smaller  in  size,  they  have,  on  the  other 
hand,  considerably  exceeded  hitherto,  in  their  average  yield  of  gold, 
the  reefs  in  the  lower  division.*  It  seems  probable,  however,  that 
the  smaller  number  of  discovered  reefs  in  the  upper  horizon  is 
largely  due  to  the  more  mountainous  and  less  accessible  character  of 
the  country  in  which  they  occur.  In  the  few  districts,  such  as 
Bright  and  the  Buckland,  where  there  has  been  any  considerable 
amount  of  prospecting  in  the  rocks  of  this  division,  large  numbers 
of  parallel  veins  have  been  exposed.  Their  greater  yield  per  ton 
*is  accounted  for  by  the  fact  that  the  ores  of  the  mines  in  the  Upper 
Silurian  are  frequently  so  charged  with  sulphides  as  to  come  under 
the  "refractory"  class,  necessitating  the  working  of  ore  of  higher 
tenor  than  is  required  in  the  Lower  Silurian,  where  the  quartz  is 
usually  of  the  simplest  "  free-milling"  type.  This  difference  will 
also  serve  to  explain  the  circumstance,  mentioned  by  the  govern- 
ment geologist,  that  all  the  largest  nuggets  obtained  in  the  alluvial 
mines  of  Victoria  have  been  found  where  Lower  Silurian  rocks 
prevail. 

The  Bendigo  district  consists,  broadly  speaking,  of  a  belt  of  sand- 
stones and  slates  of  Lower  Silurian  age,  abutting  to  the  south  and 
west  against  the  granite  of  the  Mt.  Alexander  ranges  and  overlain 
to  the  north  and  northeast  by  the  shales  of  the  Pliocene.  The  most 
marked  characteristic  of  these  sandstone  and  slate  beds  is  the  extreme 
bending,  folding,  and  contortion  which  they  have  undergone, 
accompanied,  as  might  be  expected,  by  a  varying  amount  of  fissuring 
and  faulting.  The  anticlinal  and  synclinal  undulations  are  often 
remarkably  sharp  and  exhibit  every  gradation  in  extent,  from  a  few 
feet  to  miles,  from  a  hand-specimen  to  those  larger  corrugations  of 
the  earth's  crust  which  geologists  name  "  ge-synclines"  and  ''ge- 
anticlines." The  main  anticlinal  axes  strike  N.  N.  "VV.  and  S.  S.  E., 
but  there  are  also  transverse  undulations  which  further  complicate 
the  geological  structure. 

THE  REEFS. 
The  quartz  reefs  or  lodesf  conform  to  these  folds  in  the  country- 

*  The  returns  show  that  the  average  yield  per  ton  is  as  follows  : 

Upper  Silurian,  BucWorth,  13  dwts.  23  grs.,  Gippsland  15  dwts.  21  grs. 

Lower  Silurian,  Ballarat,  7  dwts.  21  grs.,  Bendigo,  9  dwts.  5  grs. 

f  The  Australian  calls  a  quartz  lode  or  vein  a  "  reef,"  the  Californian  a  "  ledge," 
while  in  Colorado  the  word  "crevice"  often  does  similar  duty.  Throughout  this 
article  I  shall  often  use  the  colonial  mining  terns,  since  they  are  usually  expressive 
and  it  would  be  difficult  to  find  other  names  that  are  not  also  local. 


THE   BEXDIGO   GOLD-FIELD. 


17 


I    . 

Q  UJ 

5? 

ZS 

UJ 

I 

CO 


18  THE    BENDIGO    GOLD-FIELD. 

rock,  that  is,  the  ore-deposits  lie  between  and  along  the  beds  of  slate 
and  sandstone,  the  anticlinal  axes  of  which  form  the  apex  or  cap  of 
the  quartz-formations,  which  are  thus  known  as  "saddles,"  while 
the  lower  portions,  called  the  "  legs,"  similarly  dip  east  and  west 
with  the  inclosing  strata.  In  like  manner,  in  the  direction  of  their 
strike,  the  quartz-formations*  pitch  north  and  south  conformably  to 
the  longitudinal  undulations  produced  in  the  anticlinal  axes  by  the 
transverse  folds  mentioned  above. 

The  "  saddle-reef"  is  the  distinctive  ore-deposit  of  the  Sandhurst 
mines.  The  references  to  this  most  beautiful  type  of  ore-deposit  to 
be  found  among  the  works  relating  to  the  distribution  and  extraction 
of  the  precious  metals,  are  both  meager  and  inaccurate.  In  the 
Colonies,  it  is  true,  one  hears  a  great  deal  of  these  "  Sandhurst  sad- 
dles," such  references  being,  however,  for  the  most  part  very  vague, 
and  incorrect.  In  other  mining  districts,  in  the  neighboring  colo- 
nies of  New  South  Wales,  Queensland,  etc.,  the  writer  has  often 
heard  this  or  that  mine  spoken  of  as  containing  "a  saddle,  just  like 
those  of  Sandhurst."  On  examination  these  proved  in  every  case  to 
be  different  forms  of  the  ordinary  junction  of  two  lodes,  not  true  an- 
ticlines, producing  however  bodies  of  quartz  which  the  old  Bendigo 
digger  would  promptly  label  as  "saddles,"  for  the  sake,  perhaps,  of 
auld  lang  syne.  I  was  beginning  to  fear  that  the  saddle-reef  as  a 
distinct  formation  did  not  exist  at  all,  even  at  Sandhurst,  until 
underground,  at  the  New  Chum  and  Victoria  mine,  I  saw  for  the 
first  time  a  type  of  ore-deposit  which  is  perhaps  the  most  interesting 
of  the  many  forms  in  which  gold  is  known  to  occur.  I  remember 
well  my  delight  in  recognizing  the  peculiar  character  of  the  lodes, 
also  my  disappointment  on  finding  that  the  "  west  legs"  did  not 
conform  to  the  bedding,  and  then  finally  my  relief  when  I  saw  that 
in  the  latter  observation  I  had  confounded  bedding  and  cleavage. 
The  cleavage  in  some  parts  of  the  field  is  so  strong  as  to  obliterate 
the  bedding;  and  it  is  by  reason  of  this  fact  that  so  many  observers 
have  gone  astray  In  what  is  practically  the  only  authority  dealing 
with  Victorian  mining — Brough  Smyth's  Gold-Fields  of  Victoria — 
there  is  a  lamentable  confusion  upon  this  point.  The  difficulty  is 
further  increased  by  the  fact  that  there  are  "false  saddles,"  one  leg 

*  In  the  mines,  the  words  "pitch,"  "dip,"  "underlay,"  etc.,  are  used  indis- 
criminately. I  shall  always  use  "dip  "  to  express  the  angle  with  the  horizon,  east 
or  west,  made  by  the  beds  of  the  country  or  the  reefs  which  are  conformable  to 
them.  "Pitch"  will  be  used  to  describe  the  inclination  north  or  south  along  the 
strike  of  the  quartz-formations. 


THE    BEXDIGO   GOLD-FIELD. 


19 


of  which  conforms  to  the  stratification,  while  the  other  follows  a 
joint  or  some  other  cross-fracture  in  the  country.  Figs.  2  and  3 
serve  to  illustrate  the  simplest  type  of  true  and  false  saddles.  In 
both  cases  the  bedding-planes  are  indicated,  while,  to  avoid  con- 
fusion, the  lines  of  cleavage  are  omitted.  In  Fig.  2,  A  would  be 
called  the  cap  or  apex,  B  the  west  leg,  and  C  the  east  leg.  A  cross- 
cut passing  through  D  would  be  said  to  be  in  "  center-country  ;'7  ns 
soon  as  the  dip  of  the  beds  became  distinctly  east  or  west  the  cross- 


NEW   CHUM 

cut  would  have  penetrated  into  "east  "  or  "  west  country."  In  Fig. 
3,  A  A  illustrates  a  fissure,  sometimes  a  fault,  sometimes  only  a 
joint ;  D  D  is  the  ore  formed  along  this  line  of  fissure,  while  B  is 
the  body  of  quartz  formed  at  its  junction  with  the  bedding-plane 
C  C,  which  carries  another  vein  of  quartz.  When  a  formation  like 
this  is  further  complicated  by  a  few  minor  faults  and  the  develop- 
ment of  a  strong  slaty  cleavage  at  varying  angles,  it  is  very  diffi- 
cult to  determine  correctly  the  true  facts  of  the  case  ;  and  the  quartz- 
body  may  be  mistaken  for  a  true  saddle,  that  is,  an  anticline  of 
quartz. 


20 


THE    BEXDIGO    GOLD-FIELD. 


The  mines  are  located  along  the  various  "  lines  of  reef,"  which 
are  coincident  with  the  surface-exposure  of  the  quartz  formed  along 
the  anticlinal  axes.  The  general  dip  of  the  country  (as  distinguished 
from  that  of  the  individual  beds  comprising  it)  is  eastward;  or,  as 
the  miners  put  it,  "  center-country  dips  east."  The  following  state- 
ment illustrates  this  point.  Three  mines  (they  happen  to  be  three 
famous  producers)  are  taken  approximately  opposite  each  other  on 
the  three  great  lines  of  reef — the  New  Chum,  the  Garden  Gully,  and 
the  Hustlers.  In  the  accompanying  table,  the  third  column  gives 
the  average  strike  of  the  anticline  which  forms  the  "line  of  reef," 
and  the  fourth  the  pitch  of  the  quartz-formation  at  the  depths  indi- 
cated in  the  brackets.  The  last  column  gives  the  dip  of  "  center- 
country  "  as  determined  from  the  figures  given  in  columns  5  to  8. 
Taking  the  saddle  as  similar  to  the  roof  of  a  house,  the  third  column 
gives  the  angle  which  the  ridge  makes  with  the  meridian ;  tHe  fourth, 
the  angle  with  the  plane  of  the  horizon;  and  the  last  column,  the  in- 
clination of  its  axis  when  it  is  slightly  tilted  to  one  side. 

Table  showing  the  Principal  Features  of  the  Main  Saddle- Formations. 


SHAFT. 

CIH* 

O 
g 

0 

M 

B 

CO 

o 

"§   s 
'E.  '-3 

II 

43 

I 

Distance  of 
nter-country 
rom  Shaft. 

"a 

ill 

verage  dip. 

3 

< 

3 

8 

Q 

o 

< 

"180"   Mine  

New  Chum... 

21eW.ofN. 

1  in  6  (at  2500  ft.) 

MO 

«5ft.W. 

2500    TOft.E. 

Iinl4 

Victory  and  Pandora 

Garden  Gully 

25°  W.  of  N. 

Iin6  (at  650  ft.)1  140 

9  i(    " 

2160  130  "  " 

1  in  15% 

Gt.  Ex.  Hustlers  

Hustlers  

35°  W  ofN. 

1  in  5  (at  1800  ft.) 

200 

80  "    " 

1800160"  "    Iin6>£ 

1 

At  the  "  180"  mine,  for  instance,  the  strike  of  the  Chum  forma- 
tion is  21°  W.  of  N,  the  pitch  of  the  saddle  at  the  2500-foot 
level  is  northward  1  in  6,  the  dip  of  center-country  is  east  about  1 
in  14.  The  last  is  determined  thus:  at  the  560-foot  cross-cut  the 
center  country  is  65  feet  west  of  the  shaft,  while  at  the  2500  it  is 
70  feet  east  of  the  shaft,  so  that  it  has  travelled  eastward  135  feet 
in  about  1940  feet,  the  general  dip  of  the  country  having  taken  from 
one  side  to  the  other  of  this  particular  shaft  the  series  of  beds  inter- 
sected by  it.  The  ideal  section,  Fig.  4,  represents  the  structure,  and 
shows  how,  the  general  trend  of  the  country  being  to  the  east,  any 
one  of  the  deep  mine- workings  will  intercept,  in  succession,  many 
saddles,  some  of  which  will  prove  gold-bearing  and  some  barren. 
It  will  be  tunderstood  that  only  the  gold-bearing  ones  of  the  series 


THE   BEXDIGO    GOLD-FIELD. 


21 


are  developed  in  a  manner  permitting  their  proper  examination. 
One  mine  may  have  only  two  gold-bearing  saddles,  while  another 
may  have  exposed  a  dozen  or  more.*  As  soon  as  one  formation  has 
been  worked  out,  when  the  legs  intercepted  by  the  deeper  cross-cuts 
are  found  to  become  too  small  or  too  poor  for  profit,  prospecting  is 
renewed  until  another  gold-bearing  saddle  is  cut.  Its  apex  may 
occur  between  the  lower  portions  of  the  legs  of  the  last  saddle  or  it 
may  not  be  found  for  200  or  300  feet  deeper.  Deeper,  not  further 
east  or  west  on  the  same  horizon  ;  for  the  working  of  the  mine  has 


Fig.  13 


222   AND   LAZARUS. 

shown  that  a  gold-bearing  succession  of  saddles  will  go  down  in 
step-like  gradations,  each  succeeding  one  being  slightly  eastward  of 
the  one  above  it  (see  Fig.  5).  This  simplicity  of  arrangement  is,  of 
course,  much  complicated,  sometimes  utterly  destroyed,  by  faulting, 
and  by  the  formation  of  irregular  bodies  of  quartz  that  may  be  rec- 
ognized occasionally  as  imperfect  saddles. 

*  In  the  New  Chum  and  Victoria  mine,  for  instance,  as  many  as  30  saddles 
have  been  passed  through  from  the  surface  to  2300  feet.  In  the  "180"  mine,  five 
have  been  discovered  and  explored,  of  which  number  three  have  proved  profitably 
auriferous. 


22  THE    BENDIGO    GOLD-FIELD. 

As  would  be  expected  by  the  geologist,  these  anticlines  alternate 
with  synclinal  undulations;  but  this  fact  has  been  recognized  by  few 
of  those  engaged  in  the  development  of  the  field,  though  it  is  a  point 
of  paramount  importance  to  the  proper  conception  of  the  mode  of 
occurrence  of  the  quartz.  The  explanation  of  this  neglect  is  that 
exploration  has  been  confined,  particularly  in  the  deep  mines  on  the 
New  Chum  reef,  to  a  narrow  strip  of  country  in  the  immediate 
vicinity  of  the  great  anticlinal  axes;  and,  though  it  is  known  that 
quartz  lodes  occur,  for  instance,  between  the  New  Chum  and  Garden 
Gully  lines,  these  "  side-lines,"  as  they  are  called,  have  been 
neglected,*  and  it  is  in  that  portion  of  the  country  that  the  synclines 
would  be  situated.  Where  extensive  faulting  has  taken  place,  these 
synclines  are  to  be  seen  in  the  workings  of  some  of  the  mines  on  the 
main  "lines  of  reef."  In  the  Confidence  Extended,  for  instance,  I 
observed  some  small  "  inverted  saddles,"  as  also  in  the  Hercules  and 
Energetic.  In  both  cases  there  is  reason  to  believe  that  a  dislocation 
has  brought  a  portion  of  the  west  country  into  line  with  one  of  the 
chief  anticlinal  axes,  in  the  one  case  the  Garden  Gully,  in  the  other 
the  New  Chum.  A  good  instance  of  the  more  frequent  occurrence 
of  "  inverted  saddles  "  is  presented  by  the  Great  Britain  mine,  located 
on  the  Carshalton  reef,  a  "side-line"  west  of  the  New  Chum.  Fig. 
6  illustrates  it. 

The  distribution  of  the  gold  in  the  quartz  of  the  saddle-reefs 
shows  great  variations.  In  a  given  formation  in  one  mine  the  cap 
or  a  portion  of  the  cap  only  will  pay,  while  on  the  same  formation 
in  a  neighboring  claim  the  cap  and  west  leg  may  yield  good  returns, 
or  again  both  legs  may  prove  gold-bearing  while  the  cap  is  barren. 
The  quartz-bodies  do  not  extend  uninterruptedly  along  their  strike ; 
their  continuity  is  broken  by  overlappings  or  disturbed  by  faults. 
Different  local  changes  in  the  structure  of  the  country  give  very 
different  shapes  to  the  enclosed  formations. 

The  most  extensive  ore-body  and  the  greatest  yield  of  gold  from 
any  one  formation  is  claimed  by  the  Garden  Gully  line  from  a  saddle 
which  traversed  a  group  of  mines  (of  which  the  Garden  Gully 
United  and  the  Victory  and  Pandora  were  the  chief  producers),  at 

• 

*  Since  writing  the  above,  and  during  a  later  visit  to  Sandhurst,  I  learn  that  the 
recent  legislation  as  to  mining  on  private  property,  together  with  the  notable  suc- 
cess of  the  New  Red,  White  and  Blue  Consolidated,  which  is  on  a  "side  line"  (the 
Sheepshead),  has  caused  the  beginning  of  active  exploration  on  these  subsidiary 
formations,  this  exploration  being  due,  as  has  often  been  the  case  in  this  gold-field 
to  the  enterprise  of  Mr.  Lansell. 


THE   BENDIGO   GOLD-FIELD. 


23 


24  THE    BENDIGO    GOLD-FIELD. 

a  depth  of  from  600  to  700  feet  from  the  surface.  In  the  Garden 
Gully  United  alone,  it  was  worked  for  646  yards  along  the  strike 
during  14  years,  and  yielded  13  tons  of  gold.  For  continuous  pro- 
ductiveness, most  numerous  succession  of  gold-bearing  formations, 
and  greatest  underground  development,  the  New  Chum  ranks  first. 
One  can  walk  underground  from  the  Victoria  Consols  to  Golden 
Square,  through  the  continuous  workings  of  21  mines,  at  a  depth  of 
from  1800  to  2000  feet,  for  a  distance  of  2  miles.  The  average  num- 
ber of  "payable"  saddles  in  any  one  mine  on  the  New  Chum  line 
from  the  surface  to  2000  feet,  would  be  not  far  short  of  ten ;  on 
the  Garden  Gully  the  gold  has  been  practically  confined  to  two  for- 
mations. The  Hustlers  line  had  its  greatest  development  in  the 
Great  Extended  Hustlers,  the  Hustlers,  and  the  United  Hustlers  and 
Redan.  It  has  been  worked  less  extensively  than  the  other  two  main 
lines  of  reef;  but  its  known  extent  is  great,  and  it  should  prove  an 
important  producer  in  years  to  come.  Of  the  various  formations  to 
be  seen  in  the  mines  of  Sandhurst  at  the  time  of  my  inspection,  the 
largest,  most  extensive,  and  most  profitable  was  that  on  the  New 
Chum  lode  between  the  New  Chum  railway  and  the  "180"  mine. 
It  extended  through  14  different  claims  (see  Fig.  7),  a  distance  of 
2400  yards,  and  was  intercepted  at  depths  which  varied  from  1600 
to  2400  feet.  I  saw  the  development  of  this  formation  in  six  of  the 
mines  through  which  it  passed,  and,  with  the  aid  of  drawings  repro- 
duced from  sketches  made  underground,  I  will  endeavor  to  describe 
the  different  modes  of  its  occurrence. 

THE  NEW  CHUM  RAILWAY  MINE. 

The  most  southerly  mine  on  this  great  body  of  gold-bearing 
quartz  is  the  New  Chum  Railway,  which,  on  account  of  the  good 
returns  obtained  from  this  formation  at  2025  feet  depth,  is  often 
quoted  in  the  Colonies  as  an  example  of  deep  gold-mining.  From 
this  company's  ground  the  formation  rises  towards  the  Shenandoah, 
where  at  1990  feet*  the  west  leg  was  being  very  profitably  exploited 
at  the  time  of  my  visit.  In  the  breast  of  the  level  and  in  the  slopes 
overhead,  the  reef  is  seen  to  be  notably  laminatedf  and  very  well 
defined.  As  the  cap  is  approached  the  walls  remain  as  before,  but 
the  quartz  becomes  broken,  dead-white  in  color,  and  with  a  splintery 

*  It  will  be  seen  that  between  the  New  Chum  Railway  and  the  Shenandoah,  the 
back  or  anticlinal  axis  of  the  formation  pitches  about  100  feet  in  600. 

f  In  Amador  County,  Cal.,  this  would  be  called  "ribbon-rock."  In  both  Cali- 
fornia and  Australia  such  a  structure  is  considered  a  favorable  sign. 


THE    BENDIGO   GOLD-FIELD. 


25 


26  THE   BENDIGO   GOLD-FIELD. 

fracture  at  right  angles  to  the  walls.  The  cap  or  apex  of  the  saddle 
is  poor,  while  the  east  leg  soon  gets  small,  and  is  never  "  payable." 
Figs.  8,9,  10,  and  11  illustrate  the  peculiarities  of  the  formation. 
A  indicates  sandstone,  B  slate,  and  C  quartz.  Fig.  8  shows  the  west 
leg  at  the  bottom  level.  The  lode  is  about  7  feet  wide,  and  consists 
of  beautifully  laminated  and  mottled  stone,  carrying  visible  gold. 
There  is  about  4  inches  of  selvage*  or  "dig"  on  the%  hanging-wall, 
shown  at  E.  Fig.  9  shows  the  same  lode  at  the  north  end  of  the 
drift.  It  is  here  about  2  feet  wide,  closely  laminated,  but  poor. 
This  is  explained  by  the  fact  that  going  northward  the  level  gets  out 
of  the  ore-shoot,  which  is  rising  overhead,  pitching  south.  The 
"spurs"  or  feedersf  going  off  into  the  center-country  are  a  common 
feature  in  these  mines.  Fig.  10  illustrates  the  west  leg  a-few  feet 
below  the  turn-over  of  the  saddle.  The  quartz,  which  is  white  and 
barren,  shows  included  fragments  of  country  .-rock  (D).  Fig.  11 
gives  a  general  view  in  cross-section  of  the  formation.  The  richest 
ore  was  found  along  that  part  of  the  west  leg  which  is  marked  by 
crosses  (to  the  right  of  N).  The  distance  from  M  to  N  is  120  feet. 
In  the  cross-cut,  60  feet  below  the  cap  of  the  saddle,  the  legs  are  90 
feet  apart.  Center-country  consists  of  beds  of  hard  sandstone,  sepa- 
rated by  thin  slate  partings.  A  winze  sunk  below  the  cross-cut  has 
intercepted  another  small  saddle,  whose  axis  is  a  few  feet  eastward 
from  that  of  the  main  formation. 

THE  NEW  CHUM  CONSOLIDATED. 
/ 

The  next  minej  in  which  I  studied  this  formation  was  the  New 
Chum  Consolidated.  Between  this  mine  and  the  Sheuandoah  the 
formation  undergoes  a  change.  While  it  pitches  south  in  the  latter 
(as  we  have  seen),  it  turns  over  in  an  intermediate  mine,  Craven's 
New  Chum,  and  begins  to  take  a  northerly  pitch,  which  character- 
izes it  in  all  the  remaining  mines  through  which  we  shall  follow  it. 
It  is  scarcely  necessary  to  add  that  in  the  exploitation  of  the  mines 
it  is  found  that  the  back  or  anticlinal  axis  of  the  formation  has  not 

*  ''Dig"  and  "pug"  are  the  names  given  in  the  Colonies  to  that  which  an 
American  calls  "gouge,"  a  Cornishman  "hulk"  and  "  fluccan,"  and  which  in  the 
text-books  is  termed  "selvage." 

f  Irregular  cross-veins  of  quartz,  which  are  found  traversing  the  country  in  all 
directions,  are  called  at  Sandhurst  "spurs" — a  good  name,  and  almost  equivalent 
to  the  "feeders"  and  "droppers"  of  other  districts.  The  short-lived,  flat  seams 
are  often  called  "floating  spurs." 

J  See  the  plan,  Fig.  7,  of  the  mining  properties  referred  to. 


THE   BEXDIGO   GOLD-FIELD. 


27 


.•••  •m^W'f!-- ' •  •  ,# 

^liiiPtev^ 
^iiSii'^:^!;!' 
S^ill&ir-^ 


28  THE   BENDIGO   GOLD-FIELD. 

that  unswerving  regularity  which  a  general  description  might  lead 
one  to  infer,  but  is  frequently  broken  by  faults,  and  presents  over- 
lappings,  which,  however,  do  not  prevent  it  from  keeping  a  general 
easily-recognized  inclination. 

In  the  New  Chum  Consolidated,  the  formation  has  undergone 
several  changes,  as  compared  to  its  appearance  in  the  Shenandoah, 
and  one  would  be  led  to  believe  that  it  consisted  here  of  three  sad- 
dles, one  above  the  other.  If  I  read  the  facts  correctly,  there  is 
only  one,  which  corresponds  to  that  seen  above  the  1990  cross-cut 
in  the  Shenandoah.  At  the  mine,  one  is  told  that  there  is  one  con- 
tinuous west  leg,  with  three  east  legs ;  but  it  seems  to  me  th'at  it 
would  be  more  correct  to  consider  the  lower  two  legs  as  "  spurs " 
from  the  west  leg  into  the  center- country,  after  the  manner  of  the 
veins  shown  in  Fig.  9.  By  Fig.  12  it  will  be  seen  that  the  bend  of 
the  saddle  is  very  sharp,  and  that  below  the  1770-feet  cross-cut  there 
is  a  break  or  fault.  Center-country,  as  in  the  Shenandoah,  is  hard 
sandstone,  with  traces  of  a  westerly  cleavage,  while  the  bed  overlying 
the  quartz  is  slate,  which  in  the  1683-feet  cross-cut,  west  of  the  cap, 
shows  a  very  strong  cleavage  of  about  60°  east.  This  has  been 
mistaken  for  bedding,  so  that  one  is  told  that  the  saddle  is  east  of 
center-country,  and  that  the  west  leg  cuts  across  the  stratifications. 
It  is  frequently  the  case  that  in  the  immediate  vicinity  of  the  saddles 
the  cleavage  is  so  developed  as  to  hide  the  bedding-planes. 

The  richest  quartz,  or  ((  best  gold,"*  was  found  on  the  west  side 
of  the  lower  part  of  the  cap,  as  indicated  by  crosses  in  my  sketch. 
The  quartz  of  the  stopes  is  generally  very  white  and  the  gold  com- 
paratively fine.  Near  the  lode  there  is  a  casing  of  black  graphitic 
slate,  which  is  highly  pyritiferous.  In  conclusion,  it  may  be  noted 
that  in  this  mine  six  saddle-formations  have  been  discovered,  from 
the  1240  down  to  the  1810-feet  level. 

LANSELL'S  "  222  "  MINE. 

Leaving  this  mine,f  to  which  I  hope  to  refer  again  as  being  one 
of  the  best-equipped  and  best-managed  properties  on  the  field, 
the  next  claim  northward  which  I  visited^  was  Lansell's  "  222,"§ 

*  The  Australian  talks  of  ''  fair  gold,"  "good  gold,"  "  best  gold,"  etc.,  meaning 
that  he  is  getting  a  fair  amount,  a  good  amount,  etc.,  of.gold  in  the  quartz;  or,  as 
would  be  said  out  West,  '*  fairish  rock,"  '•  good  dirt,"  the  "  best  ore,"  etc. 

f  My  best  thanks  are  due  to  Mr.  James  Boland  for  his  courtesy  in  guiding  me 
through  the  mine,  etc. 

J  The  New  Chum  United  lies  between  the  New  Chum  Cons,  and  Lansell's  "  222." 

$  The  claim  is  about  222  yards  long,  while,  similarly,  the  famous  (l  180  "  mine  is 
180  yards  long.  Both  are  the  private  property  of  Mr.  George  Lansell. 


30  THE    BENDIGO   GOLD-FIELD. 

which  communicates  underground  with  the  Lazarus  mine,  so  that 
it  will  be  convenient  to  consider  both  together  In  these  two 
mines  the  overlying  beds  have  been  bent,  with  the  result  that  the 
arch  of  the  saddle  is  broken,  and  a  long  neck  of  quartz  marks  the 
fracture.  At  times,  the  formation  looks  like  an  ordinary  junction  of 
two  lod-es;  and  the  highly  developed  cleavage  would  make  it,  re- 
garded alone,  difficult  to  unravel.  At  the  1900-feet  level  in  the 
"  222,"  the  legs  are  only  20  feet  apart,  approaching  each  other 
overhead  so  that  both  are  worked  in  one  run  of  stopes,  the  heading 
of  which  presents  the  appearance  of  a  big  lode  divided  by  a  "  horse  " 
of  country.  The  quartz  itself  »is  from  5  to  20  feet  wide,  enlarging, 
of  course,  near  the  cap  of  the  saddle.  Between  the  legs  the  country 
is  quartzose,  and  much  broken  up  by  a  ramification  of  spurs  which 
with  the  cleavage  obliterate  the  bedding.  The  cap  forms  a  long  and 
narrow  neck  of  ore,  which  extends  for  81  feet  above  the  level,  break- 
ing up  "into  spurs  and  irregular  bodies  of  quartz  at  its  upper  end. 
The  formation  at  this  level  pitches  north  1  in  10. 

THE  LAZARUS  MINE. 

In  the  Lazarus,  the  cap  of  the  saddle,  forming  here  also  a  narrow 
neck  of  quartz,  was  followed  down  by  the  shaft  from  1850  to  1960 
feet,  and  proved  "  payable  "  most  of  the  way.  In  the  illustration 
(Fig.  13)  A  is  sandstone,  which,  near  the  saddle,  is  cut  up  by  spurs 
(as  is  usually  the  case  where  center-country  is  sandstone),  but  in  the 
2000-feet  cross-cut  is  hard  and  clean.  B  is  slate,  the  cleavage  of  which 
is  highly  developed.  The  arrows  (at  E  and  W)  indicate  the  bedding, 
while  the  slanting  lines  mark  the  cleavage.  E  (at  the  top  of  the 
Fig.)  is  at  1889,  and  D  at  1960  feet  below  the  surface.  C  is  the 
main  body  of  ore,  which  is  frequently  disordered  by  minor  faults, 
such  as  x  and  y.  That  marked  y,  for  instance,  carries  crushed  quartz 
3  to  4  inches  wide,  accompanied  by  softer  materials  (fluccan  or  sel- 
vage). The  spurs,  indicated  in  A,  show  gold  near  the  main  lode. 
Both  legs  and  the  cap  have  been  profitably  worked,  the  gold  in  the 
legs  being  very  coarse,  more  especially  in  the  "  west  reef/7  where 
pieces  weighing  from  1  to  3  ounces  have  been  obtained.  The  quartz 
itself  is  dead-white,  with  a  splintery  fracture,  and  when  broken 
rattles  like  fragments  of  porcelain.  There  is  but  little  pyrites  present, 
and  it  is  noteworthy  that  pyrites  is  generally  absent  from  that  part 
of  the  lode  which  carries  the  coarsest  gold.  Below  the  formation 
another  saddle  has  been  discovered,  which  may  possibly  be  that  which 
was  described  as  cut  by  the  winze  below  the  1990-feet  level  in  the 


THE  -BEXDIGO   GOLD-FIELD. 


31 


Shenandoah.  In  Fig.  11  this  u  make  of  stone  "  is  shown.  It  is  sep- 
arated by  20  feet  of  sandstone  from  the  main  saddle;  it  is  more 
regular  than  the  upper  one,  and  its  west  leg  carries  "  fair  gold," 
while  the  eastern  is  poor. 

Only  two  paying  formations  have  been  intersected  in  this  mine 
in  the  last  1000  feet  of  sinking  (that  is,  below  the  1000-feet  level), 
namely,  the  saddle  at  the  1750,  and  that  at  the  2000-feet  level  above 
described.  In  that  portion  of  the  mine  below  850  feet,  twelve  for- 


Fig.  34. 


mations  have  been  cut,  most  of  which  showed  some  gold ;  but  the 
two  above  mentioned  have  been  much  the  most  productive. 
The  following  list  may  be  of  interest: 

Saddle  cut  at  Remarks. 

850  feet, /.       . .         .         .  "  payable." 


930 
1040 
1160 
1240 
1263 
1435 
1630 
1750 
1790 
1837 


«         -         •        .«.    .•  •/    .-;  -.,.       *     *  .     .  no  good. 

.         .         .         .      •.-«         .        no  good. 

...        *        no  good. 

7  dwts.  first  crushing,  followed  by  a  4  dwt.  yield. 

•  .  « no  good. 

•  .  « no  good. 

.     *  .         .         .       small,  not  payable. 

•  *        • good. 

poor. 

broken,  poor. 


1889  to  2000  feet, very  good. 


32  THE   BENDIGO   GOLD-FIELD. 

THE  NORTH  OLD  CHUM  MINE. 

Next  to  the  Lazarus,*  is  the  Old  Chum,  which  I  did  not  visit, 
and  then  follows  the  New  Chum  and  Victoria,  which  was  not 
deep  enougnf  to  cut  the  formation  which  we  have  been  following 
through  the  different  mines.  Then  follows  the  North  Old  Chum, 
where,  at  2290  feet,  the  main  formation  has  been  profitably  devel- 
oped. A  cross-cut  at  that  depth  cut  the  west  leg  at  70  feet  from  the 
shaft,  and  45  feet  further  intercepted  the  east  leg.  A  lava  dyke 
about  4  inches  wide  is  seen  24  feet  east  of  the  west  leg.  The  west 
reef  has  been  driven  upon  for  about  20  feet  each  way.  In  the 
north  end  it  was  8  feet  wide,  with  clean  walls,  carrying  coarse J  gold, 
easily  visible  in  the  quartz  which  had  the  same  dead-white  color 
and  curious  fracture  as  that  of  the  Lazarus.  There  were  to  be  seen 
patches  of  mineral  (mostly  arsenical  pyrites)  arranged  along  the  black 
lines  formed  by  some  included  slate.  From  this  drift,  during  my 
stay  in  Sandhurst,  was  broken  stone  which  gave  "  the  deepest  divi- 
dends" on  record  for  the  Southern  hemisphere.! 

In  the  south  end  the  lode  was  smaller,  as  would  be  expected,  since 
the  saddle  pitches  north.  The  width  was  2  feet  in  the  face,  and  the 
back  of  the  level  showed  coarse  gold,  the  quartz  being  similar  to  that 
of  the  north  drift  and  accompanied  by  2  inches  of  black  clay  or 
"dig."  The  hanging-wall,  as  heretofore  in  the  other  mines,  is  seen 
to  be  slate,  while  immediately  under  the  foot-wall  there  is  "cordu- 
roy" or  closely  alternating  thin  beds  of  sandstone  of  varying  hard- 
ness and  composition.  Near  the  lode  the  country  shows  coarse 
pyrites,  arranged  with  no  apparent  regularity. 

The  east  leg  had  not  been  driven  upon  when  I  saw  it;  but  since 
then  it  has  been  developed  and  has  given  good  stone. 

When  the  north  drift  from  the  2290 -feet  level  in  the  North  Old 
Chum  has  been  driven  300  feet  further,  it  will  connect  with  the 
2300  feet  level  in  Lansell's  "  180"  mine,||  the  deepest  in  Australia. 

*  1  take  this  opportunity  to  thank  the  mine-manager,  Mr.  T.  Whitford,  for  his 
courtesy  in  taking  me  through  the  workings. 

f  Since  my  visit  the  shaft  has  been  sunk  and  the  reef  cut  at  2260  feet. 

I  The  coarse  character  of  the  gold  is  indicated  by  the  yield  of  223  oz.  of  gold 
from  only  341  oz.  of  amalgam. 

§  For  the  week  ending  September  13,  1890,  it  yielded  223  oz.  9  dwts.  from  141 
tons,  which  result  enabled  a  sixpenny  dividend  to  be  paid.  The  depth  was  2290 
feet. 

||  The  opportunity  is  offered  me  in  this  connection  to  express  my  great  obliga- 
tions to  Mr.  George  Lansell,  the  man  who  has  done  most  to  develop  the  Sandhurst 
gold-field,  for  assistance  given  me  in  visiting  the  mines,  as  well  as  for  valuable 
information  regarding  mining  and  milling  in  the  gold-field. 


THE    BENDIGO   GOLD-FIELD. 


33 


In  this  mine  the  crown  or  cap  of  the  saddle  is  cut  by  the  2200-feet 
cross-cut,  80  feet  east  from  the  shaft,  showing  a  width  of  12  feet  of 
quartz.  At  43  feet  a  dike  is  cut.  In  the  2300-feet  cross-cut  the 
west  leg  is  cut  at  58  feet,  while  the  east  leg  is  seen,  broken  up  and 
irregular,  at  130  feet.  The  dike  is  cut  at  56  feet.  In  the  2400- 
feet  cross-cut  the  west  leg  is  8  feet  east  of  the  shaft  and  the  dike  46 
feet.  In  the  2500-feet  cross-cut  this  formation  has  not  been  cut,  but 
the  west  leg  of  another  saddle  is  formed  at  48  feet  east,  the  corre- 
sponding east  leg  being  at  81  feet.  The  dike  is  at  58  feet.  In  the 
2600-feet  cross-cut  the  same  dike  occurs  at  56  feet.  The  cross-sec- 
tion (Fig.  14)  illustrates  these  formations.  The  dikes,  one  of  which 


A          Fig.  35. 

•A^MH  n  n,;')/O 

Svvl§Mt^ 

S^A^y  •":• 
-^aiw»v\\%-^T/«:-: 

PM>V^M 


is  shown  in  the  section,  are  a  most  important  and  interesting  feature 
of  the  mining  at  Sandhurst,  and  will  be  referred  to  frequently. 

THE  a!80"  MINE. 

In  the  "  180"  mine  we  see  the  furthest  northern  development  of 
the  great  saddle  which  we  have  followed  through  several  mines  and 
which  is  first  cut  by  the  New  Chum  Railway.  In  the  "  180  "  mine 
it  has  not  been  opened  up  much ;  but  at  2400  feet,  in  the  south 
level,  it  forms  the  deepest  gold-bearing  quartz  now  worked  in  the 
colonies.  The  west  leg,  the  only  portion  of  the  formation  which  is 
worked  at  present,  shows  about  1  foot  of  very  beautifully  laminated 

3 


31  THE   BENDIGO   GOLD-FIELD. 

quartz.  The  quartz  is  brittle  and  flaky,  the  gold  coarse  and  associ- 
ated with  a  good  percentage  of  iron  pyrites  and  zinc-blende.  On 
the  hanging- wall  there  is  a  black  graphitic  slate  which  carries  a  note- 
worthy amount  of  mundic.  The  foot-wall  shows  cross-joints  about 
30  inches  apart  and  nearly  at  right  angles  to  the  strike.  The  coun- 
try is  "corduroy,"  similar  to  that  noted  in  the  North  Old  Chum, 
and  carries  pyrites  near  the  reef.  The  cleavage  is  highly  developed, 
and  to  the  east  (about  60  feet)  in  the  cross-cut,  it  obliterates  the 
bedding,  though  the  latter  is  to  be  distinguished  with  difficulty  to 
the  east  near  the  east  leg  and  to  the  west  near  the  west  leg.  Be- 
tween them  the  country  is  broken  up  and  penetrated  by  the  dike, 
which  has  a  slight  easterly  dip. 

The  illustrations  represent  other  interesting  features  of  the  "  180  " 
mine.  Fig.  15  shows  the  point  where  the  lava  dike,  about  8  inches 
wide,  strikes  the  top  of  the  saddle  above  the  2500-feet  level.  The 
arrows  indicate  the  bedding;  the  slanting  lines,  the  cleavage;  E  is 
disordered  country.  The  dike  T  appears  to  be  cut  off,  but  it  finds 
a  passage  in  a  plane  other  than  that  in  which  the  section  is  taken. 
A  is  broken  sandy  rock.  O  and  C  are  fragments  of  the  cap.  Fig. 
16  is  taken  in  center-country  at  the  2500-feet  level.  The  dike  T 
(here  10  inches  wide)  cuts  through  the  spurs  preparatory  to  taking 
a  more  regular  course  conformable  to  the  bedding.  In  Fig.  14, 
already  referred  to,  the  dark  line  indicates  the  dike,  which,  though 
it  rarely  exceeds  9  inches  in  width,  has  been  traced  through  the 
half-mile  of  workings  from  the  surface  down.  It  can  be  seen  in  the 
2600-feet  cross-cut  and  it  is  a  noticeable  feature  of  a  surface  cutting, 
a  sketch  of  which  is  reproduced  in  Fig.  12.  Fig.  17  shows  the  dike 
T  where  it  forms  a  division  in  the  quartz  of  the  west  leg  (of  the 
2500-feet  saddle)  and  carries  included  pieces  of  quartz,  D.  In  this 
figure  B  is  slate,  A  is  slaty  sandstone,  and  C  is  quartz.  Fig.  18 
shows  a  fault,  the  throw  of  which  is  about  7  inches,  as  seen  in  the 
2400-feet  level.  The  sketch  explains  itself. 

The  underground  workings  of  this  very  interesting  mine*  have  un- 
covered five  saddles,  of  which  the  one  at  the  2400-feet  level  is  the  third 
"  payable"  one.  The  other  formations  were  cut  at  560,  1560,  2000 
and  2200  feet  respectively.  The  east  leg  of  the  2400-feet  formation 
is  the  longest  east  leg  in  the  mine,  40  feet.  The  longest  west  leg 
was  worked  from  the  1600  to  the  1870-feet  level.  The  cap  of  the 

*  Mr  James  Northcote,  the  mine-manager,  gave  me  a  great  deal  of  this  informa- 
tion and  in  many  other  ways  assisted  me  in  my  examination  of  the  gold-field. 


THE    BENDIGO   GOLD-FIELD. 


35 


560-feet  saddle  was  the  most  payable  portion  of  that  particular 
formation.  The  east  leg  was  short-lived,  the  quartz  pinching,  while 
the  wall  or  "back"  continued.  Generally  speaking,  the  west  legs 
are  the  strongest  and  most  auriferous  in  this,  as  in  most  of  the 
saddles  of  the  New  Chum  line  of  reef.  No  considerable  body  of 
gold-bearing  stone  has  been  worked  below  1870  feet. 

Barren  quartz  is  rarely  met  with,  but  some  is  not  of  paying  grade. 
From  1560  to  1870  feet  was  worked  the  great  saddle-reef  of  the 
"  180"  mine,  there  being  a  large  body  of  stone  or  ore  of  extraordi- 
nary richness  on  the  west  leg  of  the  formation,  which  was  first  cnt 


at  1560  feet.     The  deeper  levels  show  no  change  in  the  character  af 
the  country,  and  no  large  influx  of  water*  hinders  further  sinking. 

RECAPITULATION. 

This  concludes  that  portion  of  my  notes  which  refers  to  the  series 
of  mines  in  which  is  to  be  seen  the  main  saddle  formation  of  the 
Sandhurst  of  to-day.  It  may  be  taken  as  typical  of  the  great  runs 
of  pay-quartz  from  which  the  field  has  obtained  most  of  its  gold. 
During  the  time  (the  four  weeks  preceding  October  13th,  1890)  in 
which  I  inspected  the  larger  number  of  this  group  of  mines,  the  re- 
turns were  as  shown  in  the  accompanying  table. 


The  quantity  of  water  hoisted  is  3000  gals,  per  24  hours. 


36 


THE    BENDIGO    GOLD-FIELD. 


-~ 

MINE. 

1st  Fortnight, 
ending  Sept.  27,  '90. 

2d  Fortnight, 
ending  Oct.  11,  '90. 

For  the  Month. 

A 

I 

Loads. 

Ozs. 

Dwts. 

Loads. 

Ozs. 

Dwts. 

L'ads 

Ozs.   Dwts. 

Feet. 

2025 
1990 
1900 
1400 
1850 
1850 
1900 
1960 
1960 
2290 

New  Chum  Railway.... 

527 
385 
209 
108 
736 
416 

474 
479 
95 
45 
532 
117 

1 
3 
10 
5 
12 
11 

512 
365 
145 
160 
757 
420 

643 
379 
100 
56 
378 
72 

1 
1 
4 
14 
2 
8 

1039 
750 
354 
268 
1493 
836 
98 
441 
505 
460 

1117 

858 
195 
101 
910 
189 
88 
400 
191 
395 

2 
4 

14 
19 
14 
19 
0 
8 
0 
1 

North  Shenandoah  
Young  Chum 

New  Chum  Con  

New  Chum  United  
Lansell's  "  222" 

Lazarus  Co  

231 
256 
181 

163 
52 
743 

17 

7 
11 

210 
249 
279 

336 
138 
241 

11 
13 
10 

Lazarus  No  1  

North  Old  Chum  

Ten  mines  are  included  in  this  list,  there  being  no  crushing  from 
the  "  180  "  mine  for  this  particular  period.  The  returns  for  the 
separate  fortnights  are  given  so  as  to  show  how  far  the  yields  vary. 
Nine  out  of  the  ten  are  dividend-paying  properties  at  the  present 
time,  and  the  figures  show  that  the  average  yield  is  444  oz.  16  dwt. 
from  an  average  output  for  the  month  of  624J  loads,*  these  results 
being  obtained  from  workings  whose  depth  is  1912J  feet  from  the 
surface.  This  is  a  good  record  for  deep  quartz-mining. 

OTHER  UNDERGROUND  PHENOMENA. 

Before  proceeding  to  describe  the  underground  phenomena  ob- 
served in  others  of  the  mines  it  will  be  well  to  refer  again  to  the  gen- 
eral structural  geelogy  of  the  district.  Emmonsf  quotes  a  saying 
of  the  geologist  Von  Groddeck  that  the  understanding  of  the  true 
character  of  veins  can  only  be  arrived  at  by  study  of  the  structure 
of  the  region  in  which  they  occur.  Of  no  mining  district  can  this 
be  said  more  forcibly  than  of  Sandhurst.  As  we  have  already  seen, 
the  gold-field  is  situated  among  the  highly  contorted  folds  of  the 
Lower  Silurian  slates  and  standstones.  The  fissuring  which  is  the 
accompaniment  and  result  of  extreme  contortion  has  led  to  the  pro- 
duction of  very  diverse  forms  of  ore-deposition.  We  have  seen 
something  of  the  saddles  and  synclines  (troughs  or  inverted  saddles). 

*  A  load  is  equal  to  25  cwt.  (avoirdupois,  at  112  pounds)  of  ordinary  ore,  or  30 
to  35  cwt.  of  concentrates. 

f  "  The  Structural  Kelations  of  Ore-deposits,"  Trans.,  xvi.,  804. 


38  THE    BENDIGO   GOLD-FIELD. 

For  reasons  to  be  discussed  in  the  sequel,  the  latter  are  neither  so 
extensive  nor  so  productive  as  the  saddles  proper.  In  addition  to 
these  two  very  beautiful  types  of  ore-deposition,  there  are  in  the 
Sandhurst  mines  good  examples  of  almost  all  the  best  recognized 
forms  in  which  gold-quartz  is  known  to  occur.  When  the  parting 
between  two  adjacent  beds  has  been  a  line  of  movement,  the  distinct 
division  as  produced  in  the  country  is  recognized  and  named  a 
"  back.7'  It  is  usually  accompanied  by  a  smooth  wall  forming  the 
surface  of  the  harder  ,of  the  two  beds,  and  by  more  or  less  black 
selvage  or  gouge,  resulting  from  the  abrasion  to  which  one  of 
the  two  beds  has  been  subjected.  Such  a  "  back  "  offers  facilities  for 
the  deposition  of  quartz  by  the  waters  to  which  it  gives  a  ready 
passage.  A  "  back  "  accompanied  by  quartz,  whether  a  mere  thread 
or  several  inches  in  width,  becomes  a  "leader,"  the  word  referring 
more  particularly  to  the  quartz  seam  which  serves  as  a  guide  in 
prospecting  the  ground.  Such  a  deposit  would  come  under  the 
category  of  "  bed- veins." 

Another  very  common,  often  also  very  extensive  and  profitable, 
formation  is  locally  known  as  a  "  make  of  spurs"  It  consists  of  a 
network  of  quartz-veins,  traversing  a  more  or  less  definitely  limited 
section  of  country.  They  frequently  start  in  the  neighborhood  of  a 
"  back "  or  "  saddle,"  and  intersect  the  slate  and  sandstone  at  a 
strong  angle  with  their  bedding.  These  spurs  are  sometimes  so 
numerous  as  to  make  the  country  almost  entirely  quartzose,  while  in 
other  instances,  though  continuous  and  following  a  distinct  belt  of 
country,  they  may  be  so  far  apart  as  to  hide  their  true  character. 
In  various  forms  these  spur-systems  constitute  one  of  the  -most  im- 
portant sources  of  the  gold  obtained  in  the  Bendigo*  mines.  When 
they  accompany  one  of  the  main  reefs  they  may  be  considered  as 
"  feeders ;"  when  they  form  a  distinct  reticulation  of  quartz- veins  they 
answer  to  the  term  of  "  stockwork." 

Midway  between  the  forms  known  as  •"  backs"  and  "  makes  of 
spurs  "  come  the  "  lodes."  These  consist  of  occasional  belts  of  country- 
rock,  most  frequently  slate,  which  carry  irregular  seams  of  quartz, 
some  of  which  are  arranged  parallel  to  the  walls  (the bedding  planes 
of  the  country),  while  others  have  a  transverse  direction.  Such  oc- 
currences are  locally  called  by  the  generic  term  of  "  lode,"  differing 
from  a  "  make  of  spurs  "  in  that  the  quartz-seams  are  confined  to  one 

*  The  best-producing  mine  at  the  present  time— the  New  Red,  White,  and  Blue 
Consolidated — is  developing  one  of  these  "  makes  of  spurs." 


THE   BEXDIGO    GOLD-FIELD. 


39 


bed  alone,  and  from  the  backs  and  leaders  in  being  larger  and  less 
defined,  and  in  carrying  a  greater  proportion  of  country-rock. 

Fissures  containing  quartz  and  traversing  the  country  unconform- 
ably  to  the  bedding,  are  often  faults  and  would  answer  to  the  "  true 
fissure-vein,"*  a  type  which  is  of  frequent  occurrence  in  this  field, 
though  not  so  important  a  repository  of  the  precious  metal  as  the 
saddles  or  spurs.  "  Bulges,"  "  blocks,"  etc.,  are  names  given  to 
irregular  bodies  of  quartz,  presenting  features  more  or  less  in  common 
with  the  preceding  types.  At  Sandhurst,  as  elsewhere,  the  different 
forms  of  ore-deposition  cannot  be  arbitrarily  labelled,  exhibiting  as 
they  do  frequent  gradations  from  the  one  to  the  other.  In  the  para- 
Fig.  38. 


graphs  which  follow,  I  will  describe  instances  of  the  type  known  as 
"saddles,"  leaving  the  other  forms  for  subsequent  consideration. 

THE  SOUTH  NEW  CHUM  MINE. 

At  the  southern  end  of  the  district — about  3J  miles  from  the 
group  of  big  mines  on  Victoria  Hill,  some  of  which  have  been  passed 
in  review — there  is  a  small  mine  called  the  South  New  Chum,  which 


*  This  form  of  ore-deposit  was  at  one  time  erroneously  considered  as  particularly 
favorable  to  the  occurrence  of  continuous  shoots  of  gold-bearing  stone. 


40  THE   BENDIGO   GOLD-FIELD. 

admirably  illustrates  the  particular  formation  most  characteristic  of 
Sandhurst.* 

This  n^ine  is  working  in  regular  "saddle-country."  The  longi- 
tudinal and  cross-sections  given  in  Figs.  19  and  20  will  serve  to 
explain  it.  The  underground  developments  of  this  mine  and  its 
northern  neighbor,  have  proved  the  existence  of  three  formations, 
all  pitching  strongly  to  the  south. 

Formation  No.  1  came  to' the  surface  120  feet  from  the  South  New 
New  Chum  shaft.  The  line  drawn  in  the  section,  Fig.  19,  is  the 
anticlinal  axis  of  the  saddle.  Looking  along  the  strike,  it  would 
appear  like  the  ridge  of  a  roof,  sloping  rapidly  southward.  At  A 
the  cap  of  this  formation  was  strongly  defined  and  very  rich  in  gold. 
Near  the  surface  both  legs  proved  "  payably  "  auriferous.  At  B, 
the  saddle  was  not  "  payable."  At  C  the  cap  became  gold-bearing, 
and  was  well  denned  as  it  approached  the  next  shaft  to  the  south. 

Formation  No.  2  is  the  one  which  is  shown  in  the  cross-section, 
Fig.  20,  which  is  taken  in  a  plane  5  feet  south  of  the  line  of  the 
shaft.  Both  the  170-  and  the  2SO-feet  cross-cuts  passed  through  it. 
At  D,  Fig.  19,  the  cap  is  broken,  and  there  was  no  quartz  in  the 
legs.  At  A  the  cap  became  "  payably "  gold-bearing  as  it  ap- 
proached the  line  of  the  shaft.  The  east  leg  was  not  worked,  and 
the  west  leg  was  also  poor.  At  B  there  was  a  "  payable  "  cap  and 
west  leg,  between  the  170-  and  280-feet  levels.  At  C,  the  formation 
is  irregular  and  broken. 

Formation  No.  3  is  cut  through  by  the  shaft  and  is  again  partially 
exposed  at  the  550-feet  level.  The  cap  is  irregular.  The  west  leg 
is  worked,  but  the  east  leg  has  not  yet  been  reached  by  the  cross-cut. 
Referring  to  the  cross-section*  Fig.  20,  I  will  transcribe  the  notes 
made  by  me  while  underground. 

At  the  170-feet  level.— East  leg  cut  10  feet  east  of  shaft.  The  lower  dyke*  12  feet 
and  west  leg  34  feet,  both  west  of  shaft.  The  lower  portion  of  the  cap  is  passed 
through  in  sinking  at  125  fee  ,  the  top  of  the  cap  being  5  feet  west  of  the  shaft. 
The  lava  dike  is  4  feet  wide,  divided  by  2  to  3  inches  of  slate,  which,  through- 
out the  upper  workings,  separates  it  into  nearly  equal  portions.  The  cleav- 
age of  the  country  is  with  the  east  leg,  slightly  over  the  cap  and  stronger  a  short 
distance  above.  On  the  other  side  of  the  saddle  the  cleavage  is  decidedly  across 
the  west  leg.  The  formation  pitches  strongly  southward,  1  foot  in  6,  and  at 
times  even  1  in  5. 

*  I  owe  thanks  to  Mr.  L.  A.  Samuels,  the  mine  manager,  who  conducted  me 
through  the  workings  during  my  visits  at  the  mine  and  gave  much  interesting 
information. 


THE   BEXDIGO   GOLD-FIELD. 


41 


At  the  280/eef  level. — East  leg  74  feet  east  of  shaft.  Lava  dike  in  the  plat.* 
West  leg  84  feet  west  of  shaft.  The  dike  is  increased  in  size,  the  two  portions 
being  divided  by  two  feet  of  slate.  The  cross-cut  shows  a  subordinate  saddle  un- 
derneath the  main  formation.  This  secondary  saddle  carries  a  little  quartz  (4  to 
5  inches),  which  in  the  shaft  showed  "nice  gold."  The  west  leg  (of  the  main 
saddle)  consists  of  two  parts,  each  about  5  inches  in  width,  the  quartz  of  which  is 
very  beautifully  laminated  or  ribboned.  The  hanging-wall  is  clean  and  defined, 
inclining  at  a  less  angle  than  in  the  level  above.  The  cleavage  west  of  the  center- 
country  is  slightly  west,  nearly  upright,  and  cuts  across  the  bedding,  which  is 
readily  recognizable.  The  country  east  of  the  west  leg  is  slate  (2  feet  thick)  over- 
lying sandstone,  the  thin  bedding  of  the  latter  being  very  marked.  The  east  leg 
as  cut  in  the  cross-cut  is  small  and  poor,  but  is  overlain  by  country  corresponding 
to  that  which  covers  the  west  leg. 

Fig.  39. 


At  the  45Q-feet  level. — The  legs  of  the  upper  formation  have  not  been  sought  for, 
as  they  both  became  small  and  poor  below  the  280-feet  level.  The  east  leg;  would 
be  about  150  and  the  west  leg  200  feet  from  the  shaft.  At  35  feet  east  of  the  shaft 
a  western  "-back"  is  struck,  this  proving  to  be  the  continuation  of  a  wall  coming 
from  a  saddle  below  the  level.  The  lava  is  cut  at  36  feet  from  the  plat ;  it  here 
shows  only  a  fine  black  line  dividing  the  two  portions.  . 

At  the  ooQ-feet  level.  In  the  plat  the  sandstone  of  the  west  country  shows  ripple 
markings.  The  west  leg  of  the  third  formation  is  cut  close  to  the  shaft,  and  has 
been  driven  upon  for  118  feet  southward. 

The  east  leg  has  not  yet  been  cut,  though  the  cross-cut  has  been  put  out  in 

*  The  station  at  the  shaft,  often  called  the  "  station."  Literally,  "  plat "  means 
a  flat  place  cut  out.  The  Cornish  talk  of  a  *'  tip  plat,"  the  flat  place  where  the  ore 
is  accumulated,  with  facilities  for  discharge  below  the  level. 


42  THE   BENDIGO   GOLD-FIELD. 

that  direction  for  69  feet.  It  is  estimated  that  20  feet  more  would  find  it.  The 
cross-cut  very  clearly  shows  the  bedding  of  the  country  which  is  pierced  by  the 
lava  dikes,  which  here  are  16  feet  apart.  The  south  drift  is  on  the  west  leg. 
While  the  wall  (the  "  west  back "  of  the  450-foot  cross-cut)  continues  its  course, 
accompanied  by  a  seam  of  quartz  ("the  leader"),  the  west  ''reef"  turns  off  east- 
ward and  strikes  against  the  lava  dikes,  but  has  not  yet  been  crossed  by  them. 
The  quartz  which  here  is  highly  auriferous  is  found  to  occur  both  between  the  two 
dikes  and  west  of  them.  The  end  of  the  drift  is  in  lava. 

Figs.  21  to  27  inclusive  illustrate  some  of  the  more  interesting  of 
the  underground  features  already  referred  to.  Fig.  21  shows  the 
second  formation  as  disclosed  in  the  workings  above  the  170-feet 
level.  There  is  no  doubt  as  to  the  continuity  of  the  beds  forming 
this  anticline.  Sandstone  A  overlies  the  saddle,  of  which  B  and  D 
are  respectively  west  and  east  legs.  C  is  the  body  of  quartz  form- 
ing the  apex;  above  it  there  is  a  wedge-shaped  mass  of  crushed 
country,  consisting  for  the  greater  part  of  black  broken  slate  con- 
taining a  notable  percentage  of  pyrites,  but  no  u  payable  "  amount  of 
gold.  The  slate  underneath  the  west  leg  varies  from  2  to  3  feet  in 
thickness,  and  is  divided  by  a  thin  "bar"  (3  to  4  inches)  of  hard 
sandstone.  Underneath  the  east  leg  there  is  also  from  2  to  2|  feet 
of  slate,  while  below  the  cap  this  slate  is  irregular  and  forms 
"  bulges/'  This  bed  overlies  the  hard  sandstone  H  of  the  center- 
country,  fractured  and  penetrated  by  spurs.  The  east  back  F,  that 
is,  the  parting  which  forms  the  hanging-wall  of  the  east  leg,  has  been 
followed  for  30  feet  above  the  cap  of  the  saddle. 

Fig.  22  is  the  west  leg,  as  seen  at  the  550-foot  plat.  The  reef  C 
is  hard  against  the  back  A,  which  carries  its  own  thin  vein  of  quartz 
(the  leader).  D  D  are  spurs  from  the  west  leg  into  center- country. 
These  cross-spurs  are  a  frequent  feature  of  the  country  between  the 
legs  of  a  saddle. 

Fig.  23  represents  in  plan  the  position  of  the  "  lava  streaks"  in 
the  south  drift  of  the  550-feet  level.  S  and  T  represent  the  dikes  ; 
C  is  the  quartz ;  and  A,  A  the  "  back." 

Fig.  24  shows  the  relative  position  of  the  dikes,  as  disclosed  in 
the  550-foot  east  cross-cut-.  The  bedding  of  the  country  is  very  evi- 
dent. T,  which  is  from  18  to  20  inches  thick,  is  just  east  of  center- 
country,  and  has  cut  through  it.  S  is  20  inches  thick,  and  has  just 
begun  to  shape  its  course  with  the  bedding. 

Fig.  25  represents  the  markings,  natural  size,  in  the  decomposing 
lava  of  the  west  dyke  in  the  550  cross-cut. 

Fig.  26  shows  the  "  west  back,"  which,  40  feet  above  the  550-ft. 
level,  runs  into  the  west  leg  of  an  incomplete  saddle  (the  third  form- 


THE    BEXDIGO   GOLD-FIELD. 


43 


ation).  It  will  be  understood  that  a  "  back  "  is  such  only  so  long 
as  it  follows  the  line  of  parting  between  two  beds  of  the  country ; 
that  when  it  follows  a  quartz  seam  it  often  becomes  the  hanging- 
wall  of  a  reef;  and  finally  that,  before  striking  the  quartz  or 
after  doing  so,  it  may  change  its  character  and  be  a  cross-fissure. 
In  Fig  26,  A  is  the  back  ;  C  is  quartz;  S  and  Tare  the  two  portions 
of  the  lava  dike  which  cuts  through  the  formation.  There  is  a 
fault,  the  throw  of  which  is  from  8  to  10  inches.  The  dike  does 
not  fault  the  quartz,  but  follows  the  line  of  an  earlier  dislocation. 
D  is  broken  ground,  traversed  by  spurs.  B  is  an  east  back. 

Fig.  27  is  taken  from  the  cross-cut  at  190  feet,  and  indicates  a 
local  fault  which  throws  the  country  about  3  feet  east.     B,  B  is  a 


bed  of  slate;  F,  F  is  the  line  of  fault,  carry  ing  a  couple  of  inches 
of  selvage  and,  on  the  under  side,  a  little  quartz. 

This  mine  illustrates  the  general  character  of  the  sad  die-reefs.  To 
any  one  desirous  of  obtaining  the  key  to  the  geological  structure  of 
the  district  I  recommend  the  examination  of  formation  No.  2  as  cut 
by  the  170  and  280- ft.  cross-cuts,  where  the  different  features  of 
cleavage  and  bedding  of  the  enclosing  country,  the  pitch  and  under- 
lay of  the  quartz  bodies,  are  all  more  distinctly  marked  than  I  ob- 
served them  in  any  other  mine.  On  the  other  hand  the  lower  or 
No.  3  formation,  as  cut  by  the  450-  and  550-ft.  cross-cuts  well  illus- 
trates the  frequency  with  which  the  simpler  type  of  ore-deposits 
becomes  complicated  almost  beyond  recognition.  That  this  is  due  to 


44  THE   BENDIGO   GOLD-FIELD. 

the  action  of  faults,  is  evidenced  by  the  slickensides  on  the  walls 
and  the  crushed  condition  of  portions  of  the  country,  such  as  the 
wedge  of  slate  above  the  No.  2  saddle. 

In  this  mine  there  is  none  of  the  perplexity  occasioned  in  the  deep 
mines  on  Victoria  Hill  by  the  difficulty  in  distinguishing  the  bed- 
ding from  the  cleavage,  where  the  latter  is  highly  developed.  The 
cleavage  which  elsewhere  so  often  obliterates  the  bedding,  especially 
of  the  west  country,  is  clearly  distinguishable  in  the  slate  and  sand- 
stone beds  disclosed  by  the  different  cross-cuts. 

The  280-ft.  level,  where  it  is  driven  upon  the  western  leg  particu- 
larly, well  illustrates  this  feature.  The  sandstone  there  seen  over- 
lying the  reef  is  composed  of  a  number  of  thin  beds  of  different 
shades  of  gray  rock,  the  light  and  dark  laminae  are  beautifully  regu- 
lar, and  have  a  strong  dip  westward  (with  the  reef),  while  the 
cleavage  is  only  slightly  off  the  vertical,  giving  the  foot-wall  in  the 
"drive"  the  appearance  of  taking  a  roll.  The  side  of  the  level 
had  broken  first  along  the  wall  of  the  reef — which  is  also  the  bedding 
of  the  enclosed  country — and  then  along  the  nearly  vertical  cleavage. 

In  conclusion  I  may  add  that  though  the  mine  is  called  the  South 
New  Chum,  having  been  originally  supposed  to  be  a  southern  con- 
tinuation of  that  great  "  line  of  reef,"  it  is  now  generally  accepted 
as  being  on  an  extension  of  one  of  the  "side-lines"  to  the  west. 

THE  JOHNSON'S  MINE. 

The  finest  example  of  the  saddle-reef  to  be  seen  at  the  present 
time  is  in  the  Johnson's  mine  at  Eaglehawk.  This  claim  is  not,  like 
most  of  those  hitherto  described,  on  the  New  Chum  line  of  reef,  but 
on  the  northern  extension  of  the  Garden  Gull^  so  called  after  the 
mine  in  which  it  had  its  greatest  and  richest  development,  the  Garden 
Gully  United.  There  has  been  but  one  saddle  worked  in  the  Johnson's 
mine,  but  that  one  has  been  exceptionally  regular  and  rich.  The 
apex  is  980  feet  from  the  surface ;  the  west  leg  has  been  but  little 
developed  as  yet,  but  the  east  leg  still  continues  profitable  beyond 
the  1340-ft.  level,  which  is  the  deepest  in  the  mine. 

All  the  gold  obtained  in  the  workings  came  from  "  backs  "  and 
"  spurs,"  as  well  as  other  irregular  bodies  of  stone  or  quartz.*  De- 
scending No.  2  shaft  a  thousand  feet,  one  finds  that  the  level  is 
driven  upon  "  the  main  east  back,"  as  it  is  called.  It  may  be  con- 
sidered as  an  east  leg  which  has  no  corresponding  west  leg;  nor,  so 

*  The  Colonial  talks  of  "  stone,"  where  the  American  speaks  of  "  rock,"  and  the 
Frenchman  "  mineral."  Gold-quartz  in  Australia  is  "  golden  stone." 


THE    BE^DIGO   GOLD-FIELD. 


45 


far  as  it  has  been  followed,  does  it  turn  over  to  form  a  saddle.  This 
"  back  "  has  been  worked  successfully  for  300  feet  along  its  strike, 
the  quartz  making  in  bulges,  sometimes  100  feet  in  height,  but  of 
very  variable  longitudinal  extent.  The  gold-contents  varied  from 
3  to  10  dwt.  per  ton.  These  bodies  of  quartz  pitch  north.  Before 
coming  to  an  end  they  usually  break  up  into  a  number  of  spurs, 
and  they  are  generally  to  be  found  at  those  points  where  a  number 
of  small  veins — feeders  or  spurs — -join  the  main  back.  Such  a 
"  make  of  stone  "  *  is  to  be  seen  above  this  1000-ft.  level.  The 

Fig.  41. 


fcL^J 


1    i  ^    O     --Or  X--;:-'-v 


quartz,  12  feet  wide,  is  crystalline  and  white,  but  well  mineralized, 
containing  vugs  or  geodes  and  occasionally  patches  of  included 
country.  This  block  of  quartz  pitches  north,  but  60  feet  further  is 
another  which  pitches  in  the  contrary  direction.  A  small  regular 
seam  usually  accompanies  the  back.  It  is  known  as  the  u  leader,0 
and  is  distinct  from  the  other  irregular  bodies  of  quartz  which  may 
be  found  along  the  line  of  the  back.  The  terms  "  back  "  and 
"  leader  "  are  used  interchangeably.  The  wall  of  the  back  is  very 
well  defined,  and  carries  a  couple  of  inches  of  black  clay — the 
"  dig  " — which  continues  long  after  the  quartz  has  died  out.  Figs. 
28  and  29  will  illustrate  this.  A  is  sandstone  ;  C  is  massive  quartz ; 
B  is  slate  ;  L  is  the  leader  ;  D  is  the  dig  or  selvage  ;  F,  F  are  small 
spurs.  A  cross-cut  85  feet  east  from  this  back  brings  us  to  the  east 

*  A  "  make  of  stone"   is  the  equivalent  of  a  "shoat  of  ore"  or  an  "ore-body." 


46  THE   BENDIGO    GOLD-FIELD. 

leg  of  the  big  saddle.  The  cross-cut  shows  that  on  the  hanging-wall 
there  are  14  feet  of  sandstone,  divided  by  three  thin  partings  of 
slate.  Both  walls  are  very  clean  and  distinct,  the  hanging  par- 
ticularly. 

Above  the  stopes  the  saddle  itself  is  seen.  The  appearance  of 
the  workings  is  very  striking.  The  removal  of  the  quartz  has  left 
a  large  vaulted  chamber,  over  which  the  curving  hanging- wall  ex- 
tends with  the  regu[arity  of  an  arch  of  masonry,  while  the  foot-wall 
underneath  looks  like  the  back  of  a  boiler,  the  curve  of  the  saddle 
being  remarkably  regular.  As  there  is  no  timbering  to  obstruct  the 
vein,  it  is  easy  to  sketch  the  heading.  Fig.  30  shows  the  general 
structure  of  the  formation.  Looking  along  the  crest — the  summit 
of  the  curving  under-wall — one  can  readily  see  that  the  piteh  is  to 
the  north.  The  overlying  rock  is  the  hard  sandstone  which  forms 
the  hanging-wall ;  underneath  comes  2J  feet  of  quartz ;  then  follows 
a  dark  parting  of  slate,  under  which  lies  12  to  14  inches  of  sand- 
stone, then  5  to  6  inches  of  slate,  mixed  up  with  quartz,  which  latter 
gets  rapidly  smaller  both  east  and  west. 

These  layers  of  slate,  sandstone  and  quartz  are  all  conformable  to 
the  bedding  of  the  enclosing  country.  The  over- arch  ing  wall  of 
sandstone  shows  wavy  markings,  a  suggestion  of  the  beautiful  rip- 
ple-markings to  be  seen  at  the  1060-ft.  level.  There  are  also  to  be 
observed  thin  threads  of  quartz,  in  lines  at  right  angles  to  the 
strike — probably  following  joint-planes. 

The  west  leg  has  been  followed  only  30  feet  on  the  dip.  Fig.  31 
illustrates  its  appearance.  Under  the  hanging  is  12  to  14  inches  o'f 
clean  quartz,  C,  well  laminated.  Underneath  comes  2  feet  of  sand- 
stone, A,  separated  by  a  black  slate  parting.  Between  this  sand- 
stone and  the  main  foot-wall  there  is  5  inches  of  slate,  B.  The 
hanging  is  broken  by  feeders  which  carry  gold.  The  cleavage  of 
the  country-rock  is  to  the  east,  as  indicated  ou  the  right  of  the 
drawing. 

The  east  leg  has  supplied  the  major  portion  of  the  output  of  the 
mine,  and  has  proved  highly  auriferous.  Fig.  34  shows  its  appear- 
ance just  below  the  cap  of  the  saddle.  The  reef  at  this  point  is 
divided  into  two  parts  by  about  12  inches  of  sandstone,  H.  The 
upper  portion,  C,  is  2J  feet  wide,  mottled  by  the  inclusion  of  bits  of 
country,  M,  near  the  hanging-wall,  and  well  laminated  or  ribboned 
(N)  near  the  included  sandstone,  H,  which  last  is  cut  up  by  spurs, 

s,  s. 

The  underlying  slate,  B,  is  black  and  graphitic.     The  lower  por- 


THE   BENDIGO   GOLD-FIELD.  47 

tion,  E,  of  the  reef  is  less  regular,  and  lies  directly  upon  the  hard 
sandstone,  D,  of  the  main  foot-wall.  At  about  40  feet  below  the 
cap  the  east  leg,  as  seen  in  Fig.  32,  pinches  to  3  inches  at  C,  with  4 
feet  of  slate,  B,  and  sandstone,  A,  between  it  and  the  hanging.  The 
decrease  in  size  is  compensated  for  economically  by  an  increase  in 
the  gold-contents. 

At  the  1065-foot  level  the  lode  has  been  worked  out.  At  the 
1280-foot  level  a  cross  course  throws  the  east  leg,  which  is  here  from 
9  to  10  inches  wide,  eastward  6  feet,  which  is  equivalent  to  its  being 
moved  from  one  wall  to  the  other  of  the  lode-channel  in  which  it  is 
situated.  This  is  shown  in  Fig.  33.  At  this  point  a  body  of  quartz, 
C,  about  6  feet  by  6  feet,  is  formed.  It  is  very  white,  and  has  been 

Fig.  42. 


Fig.  43 


known  to  carry  coarse  gold.  A  is  sandstone;  B,  slate ;  R,  the  reef. 
The  north  end  of  the  1280-foot  drive  shows  two  faults*  in  the  lode. 
See  Fig.  35.  The  larger  has  a  throw  of  8  inches.  Both  dip  west- 
ward, but  at  different  angles.  The  quartz,  A,  on  the  foot- wall  side, 
is  much  the  best  in  appearance  and  in  yield.  The  foot-wall  itself  is 
well  defined  and  unbroken.  B  is  broken,  slaty  rock,  containing 
pieces  of  quartz.  C  is  a  body  of  quartz,  white,  and  containing  but 
little  gold. 

In  the  stopes  the  same  faults  are  found  closer  together.   The  spurs 

*  In  the  mine  they  call  them  "slides."  Elsewhere  in  Australia  this  term  alter- 
nates with  "heads"  and  <%  breaks."  In  the  Xew  Zealand  coal-mines  the  synonym 
is  "  troubles." 


48  THE   BENDIGO   GOLD-FIELD. 

in  the  foot-wall  going  west  from  the  reef  pay  to  follow  for  20  or  25 
feet.  The  quartz  of  which  they  are  formed  is  white  and  the  gold  is 
coarse,  not  varying  in  this  regard  whether  near  or  distant  from  the 
main  lode.  The  tenor  of  the  ore  is  such  that  the  reef  will  pay  to 
work  when  only  3  inches  thick,  the  miners  breaking  with  it  feeders, 
spurs,  mullock,*  everything  as  it  comes.  The  average  width, 
however,  is  from  12  to  16  inches,  at  which  size  the  lode  is  most 
gold-bearing, — better  than  when  it  increases  to  its  maximum  width 
of  3  feet. 

At  the  1340-feet  level  the  east  leg  is  still  rich  in  gold.  It  is  be- 
coming more  inclined,  having  travelled  east  10  feet  in  the  last  60, 
while  between  the  1000-  and  1280-feet  levels  it  moved  90  feet. 
There  is  not  so  much  country-rock  between  the  walls  as  in  the  levels 
above.  The  quartz  is  covered  by  a  very  clean  striated  hanging- wall, 
which  is  4J  feet  west  of  the  main  hanging  of  the  lode-channel.  In 
the  breast  of  the  north  drift  the  reef  is  6  feet  wide.  The  foot-wall 
is  a  sandstone  so  far  altered  and  hardened  as  to  be  a  quartzite.  Rip- 
ple-marks are  beautifully  distinct.  There  is  a  fine  line  of  stopes 
above  this  level.  Faults  similar  to  those  in  the  1280  are  seen.  The 
broken  country  under  the  faults  shows  evidence  of  having  been 
arranged  in  lines  parallel  to  the  lode.  In  the  south  drift  is  seen  the 
lava  dike,  shown  in  Fig.  36.  B  is  a  fault,  the  course  of  whjph  is 
marked  by  soft  broken  slate.  The  reef,  A,  is  twice  dislocated,  the 
second  time  by  a  small  fault,  which  has  served  as  a  passage-way  for 
the  dike,  T. 

This  1340-feet  level  is  at  present  the  deepest  in  the  mine.  The 
reef  has  been  followed  by  a  winze  for  a  further  depth  of  35  feet. 
The  shaft  is  now  being  sunk  so  as  to  enable  deeper  levels  to  be 
opened,  and  so  continue  the  development  of  the  mine.  A  cross-cut 
is  being  driven  to  intercept  the  west  leg. 

The  richest  ore  which  this  formation  yielded  was  obtained  just 
below  the  turn-over  of  the  saddle,  but  very  rich  shoots  were  found 
irregularly  distributed  through  the  reef,  having  the  same  pitch  as 
the  formation  itself.  The  quartz,  speaking  generally,  is  patchy,  and 
sometimes  extremely  rich  bunches  are  found.  One  of  these  lately 
gave  150  ounces  of  gold  from  a  half-sack  of  quartz. 

*  Mullock  is  waste  rock.  A  "mullock-tip"  is  brother  to  the  western  "  dump." 
Originally,  mullock  was  the  name  given  to  the  basalt  which  covered  the  deep  leads 
of  Ballarat;  but  since  then  the  alluvial  diggers  have  introduced  the  term  into 
quartz-mining  ;  and  at  Sandhurst  it  refers  to  the  slate  and  sandstone  which  is  broken 
with  the  quartz  of  the  reef. 


THE    BEXDIGO    GOLD-FIELD. 


49 


As  we  have  seen,  most  of  the  workings  are  on  the  east  leg,  which, 
as  observed  in  the  levels  underneath  the  cap  of  the  saddles,  presents 
all  the  appearance  of  an  ordinary  quartz-lode  with  walls  parallel  to 
the  bedding  of  the  enclosing  country.  The  cross-cuts  show  the  bed- 
ding. The  alternating  slate  and  sandstone  are  called  "bars"  by 
the  miners.  Thus,  one  hears  of  a  cross-cut  having  just  passed 
through  a  "  tight  bar  of  sandstone."  Even  where  the  difference  in 
the  nature  of  the  rock  forming  adjacent  beds  is  very  slight,  there  are 
lines  of  parting  (usually  seams  of  slate)  which  indicate  the  stratifi- 


cation.    The  cleavage  is  distinct  and   uniformly  to  the  east  at  an 
angle  of  60°. 

The  Johnson's  mine  for  the  half-year  ending  June  30,  1890,  paid 
dividends  amounting  to  £19,441  2s.  The  yield  of  12,367  loads  of 
stone  was  9146  oz.  3  dwt,  worth  £38,639  5s.  3d.,  and  averaging  14 
dwt.  19  gr.  per  load.  The  following  figures  will  be  of  value  as  in- 
dicating the  tenor  of  the  ore  at  the  different  levels  during  the  half- 
year  : 

Part  of  the  Mine. 

Above  the  550-feet  level,  .  l      . 
1000-feet  level, 
1130-feet  level, 
1200-  and  1210-feet  levels, 
12SO-feet  level, 
1340-fei-t  level, 

4 


Loads. 

Yield. 

(About  2800  Ibs:  each.) 

Oz.   dwts. 

.       121 

13     10 

.     1886 

991       3 

.       289 

206     16 

s,        .     2156 

1274     17 

.     5145 

3276     17 

.     2113 

2803     19 

50  THE   BENDIGO   GOLD-FIELD. 

The  average  yield  from  the  stone  at  the  bottom  of  the  mine  was  1 
oz.  7  dwt.  per  load.* 

The  Johnson's  mine  is  on  the  Garden  Gully  line  of  reef,  but 
the  next  to  be  described  is  on  the  third  of  the  three  great  anti- 
clinal axes — the  Hustlers.  The  Great  Extended  Hustlers  is  one  of 
the  "  record-mines"  of  the  district,f  and  at  the  present  time  exhibits 
a  formation  of  subsidiary  saddles  which  is  both  peculiar  and  inter- 
esting. Fig.  37  illustrates  the  formation  as  it  is  seen  in  the  workings 
between  the  1700-  and  1800-feet  levels.  The  cross-section  is  taken 
along  a  6,  and,  with  the  longitudinal  section,  will  explain  itself.  A 
is  slate,  B  and  C  are  both  sandstone.  It  is  seen  that  the  anticlinal 
axes  (the  ridges  of  the  saddles)  pitch  strongly  to  the  north,  the  main 
axis  1  in  5,  while  the  secondary  saddles  pitch  1  in  3.  The  main 
formation  has  been  worked  for  800  feet  in  this  mine,  and  extends  for 
some  distance  into  the  adjoining  claims.  The  secondary  saddlesj  have 
a  length  along  their  strike  of  250  and  300  feet  respectively. 

In  Fig.  37  it  is  seen  that,  commencing  at  the  south,  the  right  hand 
of  the  drawing,  a  cross-section  would  show  one  large  saddle;  as  we 
proceed  north  the  great  width  of  quartz  becomes  divided  by  a  horse 
of  sandstone  which,  like  a  wedge,  eventually  splits  the  formation 
into  two  saddles,  having  at  a-b  a  width  through  their  caps  of  40 
and  12  feet  respectively.  At  this  point  the  top  of  the  main  cap 
is  irregular,  broken  into  a  mass  of  spurs.  The  foot-wall  of  the  lower 
saddle  forms  a  very  clean  arch.  Further  north  again,  the  lower 
saddle  gradually  pinches  out,  while  simultaneously  the  main  forma- 
tion increases  in  size,  very  soon  to  be  again  divided  by  another  wedge 
of  country-rock,  with  repetition  of  the  conditions  already  noted  in  the 
previous  case. 

Before  the  two  saddles  become  divided  by  the  country-sandstone, 

*  My  thanks  are  due  to  Mr.  Williams,  the  mine-manager,  as  also  to  the  under- 
ground foreman,  for  the  details  here  given. 

f  It  is  a  noteworthy  fact  that  the  three  mines  which  perhaps  rank  first  in  the 
returns  of  gold  which  they  have  made,  should  be  on  the  three  main  "lines  of  reef," 
and  opposite  each  other,  illustrating  the  old  mining  aphorism,  "ore  against  ore." 
I  refer  to  the  "  180  "  on  the  New  Chum,  the  Garden  Gully  on  the  line  of  the  same 
name,  and  the  great  Extended  Hustlers  on  the  Hustlers  line. 

%  During  my  later  visit  to  Sandhurst  the  manager  informed  me  that  he  had  come 
across  a  third  of  these  subsidiary  saddles.  I  had  not  the  time  to  inspect  it.  I  have 
here  an  opportunity  of  thanking  the  mine-manager,  Mr.  Thomas  Heckley,  for  the 
valuable  assistance  he  gave  me  in  visiting  this  mine,  as  well  as  for  his  guidance  in 
examining  the  old  working*  of  the  Unity  mine. 


THE   BENDIGO   GOLD-FIELD. 
Fig.  45 


51 


188    FT.  CROSSCUT- 


894   FT.  CROSSCUT- 


UNITY   MINE. 


»53    FT.  CROSSCUT. 


SCALE.    1  =  40'' 

E3QUART2  _LAVA  DYKES 

^2S38AMD8TONE        [T^)  SLATE 


atM. 


52  THE    BENDIGO    GOLD-FIELD. 

the  main  body  of  the  quartz  begins  to  show  included  fragments  of 
country ;  becomes,  as  the  Sandhurst  miners  say,  "  mullocky."* 

At  the  1750-feet  level,  the  east  leg  carries  three  or  four  inches  of 
quartz  against  a  sandstone  wall  which  exhibits  transverse  markings. 
These  will  be  referred  to  later.  The  quartz  is  crushed  so  as  to  re- 
semble common  table-salt,  and  occasionally  the  surface  where  it  has 
not  been  pulverized  shows  beautiful  slickensides,  polished  to  the 
likeness  of  ivory,  and  veined  with  black  streaks  due  to  the  grinding 
of  the  pyrites.  The  west  leg  shows  a  large  body  (5  to  6  feet)  of 
white  and  splintery  quartz. 

The  saddle  was  most  auriferous  at  and  immediately  below  the 
commencement  of  the  legs.  This  was  particularly  marked  in  the 
case  of  the  west  leg,  which  was  by  far  the  more  auriferous  of  the 
two.  In  another  formation,  worked  in  the  levels  immediately  over- 
head, the  reverse  was  the  case ;  the  east  leg  paid  best,  often  proving 
continuously  gold-bearing  for  from  150  to  200  feet;  whereas  the 
east  legs  are  generally  short-lived. 

The  sandstone  overlying  the  saddle  is  10  to  15  feet  in  thickness, 
and  is  overlain  by  a  bed  of  slate  25  feet  thick  over  the  cap,  and 
penetrated  lower  down  by  the  1800-feet  cross-cut,  the  slate  being 
thinner  on  the  west  side  than  on  the  east,  where  it  is  much  disturbed 
arid  broken. 

The  sandstone  over  the  cap  has  a  nearly  vertical  cleavage ;  that 
of  the  west  country  is  strongly  east,  while  that  of  the  eastern  country 
.is  slightly  westward  ;  in  other  words,  the  cleavage  is  radiated.  This 
is  illustrated  in  Fig.  38. 

In  Fig.  39,  one  of  the  lower  secondary  saddles  is  shown.  The 
cleavage  over  the  cap  is  also  radiated  and  distinct,  though  it  does 
not  entirely  hide  the  bedding.  Above  the  cap,  at  B,  and  in  the 
quartz  itself,  at  C,  there  are  a  few  inches  of  black  slate.  In  the 
center-country  underneath,  there  is  the  suggestion  of  a  third  saddle, 
D,  in  the  quartz  seam  following  the  slate-parting  which  marks  the 
bedding  of  the  sandstone. 

Fig.  40  is  taken  in  the  1805-feet  level.  A  B  is  a  bedding-plane, 
sandstone  above  and  slate  underneath.  The  lines  C,  C,  are  joint- 
fractures  ;  S,  S,  are  small  spurs  cutting  across  both  divisions  in  the 
country-rock.  Underneath  the  second  saddle  in  the  same  level  are 
seen  the  fractures  shown  in  Fig.  41 ;  A  B  is  the  east  leg,  C  is  a 
quartz  seam  following  the  bedding  ;  a  a  are  lines  of  normal  cleavage. 

*  That  is,  mixed  with  mullock  or  country-rock. 


- . 


54  THE    BENDIGO   GOLD-FIELD. 

The  system  of  fractures  to  which  b  b  belong  appears  to  me  to  be  also 
cleavage,  but  due  to  the  transverse  (north  and  south)  folding  of  the 
country.  In  other  words,  there  is  here  double  cleavage,  one  due  to 
the  east  and  west,  and  the  other  to  the  north  and  south,  bending  of 
the  beds.  The  planes  b  b  are  at  right  angles  to  the  plane  of  A  B 
(the  bedding)  and  are  not  confined  to  the  bed  only. 

Reference  has  been  made  to  some  peculiar  markings  seen  above 
the  east  leg  of  the  main  formations.  They  are  more  plainly  seen  in 
the  sandstone  above  the  west  leg  at  and  about  the  turn-over  of  the 
saddle.  As  seen  underground,  they  present  the  appearance  shown 
in  Fig.  42.  The  deepening  and  thinning  of  the  dark  lines  is  due 
to  the  unevenness  of  the  surface  produced  in  breaking  it.  Actually, 
the  lines  are  as  shown  in  Fig.  43.  They  are  identical  with  the 
cleavage,  and  present  an  instance  of  cleavage  which  is  also  crystalline 
lamination,  that  is,  they  are  lines  due  to  compressive  strain,  along 
which  a  dark  indeterminate  mineral  has  been  developed  and  arranged. 

Fig.  44  is  a  "  false  saddle"  seen  in  the  1670-feet  level.  B  is  slate, 
the  cleavage  of  which  is  indicated,  as  is  also  that  of  A,  which  is  a 
slaty  sandstone.  T  is  a  lava  dike,  12  to  14  inches  wide.  D  is  a 
slaty  sandstone,  broken  up  and  containing  irregular  fragments  of 
quartz  at  E,  E.  The  bedding,  to  the  west,  is  indicated  by  the  arrow. 
This  is  a  typical  instance  of  a  quartz  formation  which  is  very  apt  to 
be  mistaken  for  a  true  saddle.*  Quartz  is  formed  along  the  fissure 
which  cuts  across  the  bedding  of  the  country,  the  bedding-planes 
themselves  also  show  quartz,  and  the  point  of  intersection  with  the 
fissure  may  be  marked  by  a  large  body  of  ore.  In  this  case  the 
dike  follows  the  line  of  the  cross-fissure  and  a  formation  of  quartz 
(C)  is  seen.  It  is  to  be  noted  that  the  line  of  bedding  is  more  favored 
in  the  deposition  of  quartz  than  that  of  the  fissure  which  crosses  it. 
Such  "  makes  of  stone  "  are  notably  irregular  and  uncertain.  At 
the  point  where  the  sketch  is  taken  the  lava  is  just  west  of  "center- 
country/1  and  the  reef  underneath  the  lava  is  of  very  limited  extent. 
In  going  south,  the  dike  makes  over  to  the  east  country,  the  country 
dipping  east,  and  the  accompanying  quartz  then  becomes  more  contin- 
uous. 

THE  UNITY  MINE. 

At  the  Unity  mine,  which  is  on  the  Garden  Gully  line,  there  is  a 
good  example  of  the  extensive  faulting  which  frequently  obtains  in 
this  district,  making  difficult  the  development  of  the  ore-bodies. 

*  As  already  noted  in  the  beginning  of  this  paper. 


THE    BENDIGO    GOLD-FIELD. 


55 


Fig.  45  is  a  section,  40  feet  to  the  inch,  which  will  serve  to  explain 
the  occurrence.  B  A  C  is  an  imperfect  but  true  saddle,  since  the 
country  dips  east  and  west  with  the  two  legs.  There  is  no  true  east 
leg,  but  rudiments  of  it  are  seen  in  the  spurs  which  traverse  the 
slate  at  S.  Sandstone  overlies  the  cap  and  the  west  leg,  as  well  as 
the  bed  of  slate  in  which  are  the  spurs  which  replace  the  east  leg. 
At  28  feet  below  the  cap,  the  country  is  faulted,  the  throw  bringing 
the  west  leg,  the  only  part  of  the  formation  which  continues  well- 


Fig.  52. 


VICTORY  AND   PANDORA 

COMPARATIVE    SECTIONS 


SCALE    ABOUT    4o'-. 

.  LAV*    DYKE 


defined,  from  B  to  D,  a  distance  of  35  feet.  Another  slide  at  a 
further  depth  of  38  feet  (along  the  dip)  causes  another  break,  this 
time  of  8  feet  only.  Again  at  M  there  is  a  dislocation,  which  has 
not  gone  further  than  to  cause  a  derangement  in  the  straight  course  of 
the  lode.  We  will  follow  the  formation  through  the  different  changes 
which  it  undergoes.  At  the  183-feet  cross-cut,  where  it  is  first  seen, 
the  top  of  the  cap  has  been  stoped  away,  offering  to  view  the  partial 


56  THE   BEXDIGO   GOLD-FIELD. 

formation  of  the  arched  structure,  which  is  so  beautifully  distinct  in 
some  of  the  mines,  the  Johnson's  for  instance.  The  west  leg  is 
strongly  defined,  and  yielded  well  at  the  time  it  was  stoped.  The 
spurs  which  replace  the  east  leg  were  worked  for  a  depth  of  25  feet, 
and  eventually  merge  into  the  formation  shown  at  C  in  Figs.  45  and 
46.  In  the  latter,  A  is  the  sandstone  of  the.  overlying  country  ; 
E  E  are  spurs ;  C  is  quartz,  which  includes  several  fragments  of 
country  at  D  D ;  B  is  a  layer  of  brecciated  quartzose  material  con- 
taining gold,  whose  origin  was  probably  the  fragments  of  quartz 
broken  away  by  the  fault  from  the  west  leg  up  above.  All  this 
overlies  the  lava  dike  T,  which  is  from  6  to  8  inches  wide,  and  is 
separated  from  the  underlying  sandstone  by  the  lower  wall  of  the 
fault-fissure.  The  whole  formation,  inclusive  of  the  portions  C,  D, 
B,  may  be  considered  as  forming  the  slide  or  fault  which  at  a  later 
date  became  a  passage-way  for  the  dyke.  The  west  leg  continues, 
well-defined  and  easily  recognizable,  fora  depth  of  over  200  feet,  in 
spite  of  its  being  three  times  dislocated.  From  D  to  F  it  forms  a 
large  body  of  stone,*  decreasing  from  12  to  5  feet  in  width,  which 
yielded  good  returns,  many  crushings  giving  5  oz.  per  ton. 

At  the  290-feet  level  at  the  east  end  of  the  cross-cut,  the  first  fault 
is  seen.  A  drift  15  feet  long  shows  at  its  opposite  ends  the  appear- 
ance illustrated  in  Figs.  47  and  48.  Fig.  47  shows  the  south  end. 
The  sandstone,  A,  is  over  the  line  of  fault,  which  along  its  course 
has  a  clean  wall  carrying  a  few  inches  of  soft  selvage,  S.  The  sand- 
stone, C,  underneath,  is  considerably  fissured,  and  in  the  fissures  are 
the  small  quartz-seams,  m,  m.  The  slate,  B,  shows  cleavage  parallel 
to  the  fault.  Quartz  is  formed  along  the  main  wall,  and  a  large 
spur,f  D,  follows  the  bedding  of  the  country.  At  the  other  end  of 
the  drive,  only  15  feet  from  the  south  face,  the  heading  presents  a 
totally  different  appearance,  as  is  shown  in  Fig.  48.  A  is  sandstone ; 
T  is  the  dike  which,  in  the  plane  of  section,  Fig.  47,  must  have 
pinched  out  temporarily.  D,  D  are  quartz-veins  parallel  to  the 
fault.  The  country  through  which  it  cuts  dips  east. 

The  291 -feet  cross-cut  gives  a  section  of  the  lode  and  of  both 
slides.  The  lower  fault  is  28,  and  the  first,  or  upper,  57  feet  east  of 
the  shaft.  The  second  fault  has  more  dip,  but,  like  the  first,  it 
shows  a  bulge  of  lava  at  one  end  and  none  at  all  at  the  other  end,  6 

*  That  is,  "  mill-stuff/'  "  quartz,"  or  "  dirt,"  as  it  is  variously  termed  by  the  miners 
in  various  parts. 

f  Were  it  to  continue  for  any  distance  it  would  be  called  a  "  back,"  since  it  fol- 
lows the  line  of  bedding. 


THE   BEXDIGO   GOLD-FIELD. 


57 


feet  distant,  of  a  raise  which  has  been  put  up  to  cut  the  lode.  The 
country  between  the  two  slides  is  much  disturbed,  and  shows  lines 
of  fissure  in  sympathy  with  the  faults.  It  is  full  of  flat  spurs,  hav- 
ing a  slight  dip  eastward.  The  country  west  of  the  faults  contains 
no  spurs,  but  it  is  hard  sandstone  and  much  fissured.  At  15  feet 
west  of  the  second  fault  or  slide,  the  country  begins  to  show  a  west- 
erly dip.  In  Fig.  49,  taken  at  this  point,  a,  a  are  fissures  parallel 
to  the  faults;  b,  b  is  the  bedding,  indicated  by  a  slate  parting  be- 
tween two  layers  of  sandstone ;  c,  c  is  cleavage,  nearly  vertical. 

At  the  353-feet  level  (see  Fig.  45)  the  quartz  has  decreased  to  2J 
feet,  but  it  is  still  a  strong  lode.  Neither  of  the  faults  is  to  be  seen, 
as  the  cross-cut  is  not  far  enough  east.  At  M  there  is  seen  an  at- 
tempt at  faulting  which  has  gone  so  far  only  as  partially  to  dislocate 


Fig.  54. 


RIPPLE   MARKS. 
JOHNSON'S   MINE.   ioes  .FT.  LEVEL. 

the  reef.  At  N  there  is  a  "  back,"  a  line  of  parting  between  two 
beds,  parallel  to  the  lode,  which  goes  up  as  far  as  the  second  fault, 
where  a  formation  of  spurs  is  found  on  both  sides  of  it.  This  is  the 
last  we  see  of  the  reef,  which  decreases  rapidly  in  size  and  becomes 
unprofitable,  the  dip  taking  it  across  the  shaft  before  reaching  the 
level  of  the  451 -feet  cross-cut. 

This  cross-cut  intercepts  at  O,  Fig.  45,  the  back  which  we  saw  at 
N,  in  the  353-feet  crass-cut.  It  is  well-defined  and  continues  under 
foot.  The  cross-cut  ends  in  a  very  well-formed  saddle,  P,  Q,  K, 
which  is  shown  in  greater  detail  in  Fig.  50.  The  outline  is  sug- 
gestive of  a  double  contortion.  The  cap  makes  a  very  clean  curve. 
Sandstone,  A,  overlies  the  quartz,  both  being  penetrated  by  the  dike, 
T.  Underneath  the  quartz  is  slate,  B,  in  which  are  the  spurs  at  C, 
which  replace  the  east  leg.  The  west  leg  is  divided  into  two  por- 
tions, separated  by  slate.  Going  south,  they  are  wider  apart.  The 


58  THE   BENDIGO   GOLD-FIELD. 

slate  under  the  cap  shows  lines  of  bedding,  and  its  division  from  the 
underlying  sandstone  forms  a  clean,  very  beautiful  arch. 

The  lava  dikes,  which  form  so  marked  a  feature  of  the  section, 
Fig.  45,  have  many  points  of  interest.  A  dike  (varying  from  12  to 
20  inches  in  size)  cuts  through  the  cap  at  the  183- feet  level.  It  has 
a  slight  eastern  dip  which,  on  striking  the  quartz,  is  changed  for  the 
dip  of  the  west  leg,  through  which  it  passes  (it  is  now  6  to  8  inches 
wide)  until  meeting  the  fault,  which  it  then  follows,  as  the  line  of 
least  resistance.  It  underlies  the  formation  at  C,  and  is  last  seen  in 
the  294-feet  cross-cut. 

Another  dike  (4  inches  only  in  width)  comes  down,  keeping  com- 
pany with  a  "  leader,"  cut  near  the  shaft  at  the  294-foot  level.  It 
is  probably  a  branch  from  that  which  follows  the  No.  2  fault,  as 
seen  at  H,  Fig.  45.  This  latter  dike  is  probably  again  seen  in  the 
lava  which  strikes  at  Q  against  the  saddle,  following  the  west  leg 
for  a  few  feet,  and  then  cutting  across  the  quartz  to  continue  its 
course  through  the  sandstone  of  the  center-country. 

At  the  353-feet  level,  near  the  plat,  is  seen  the  dike  shown  at  K, 
which  is  also  illustrated  in  Fig.  51.  There  it  is  seen  that  it  cuts 
across  the  bedding  (A,  A),  following  a  fissure,  and  that  it  appears  to 
die  out  in  small  threads  at  M  and  N. 

About  5  feet  east  of  this  point  there  is  another  dike,  shown  at  Z, 
Fig.  45,  which  is  9  inches  thick,  and  is  continuous  so  far  as  it  is 
seen. 

The  two  faults  encountered  in  this  mine  are  found  again  in  the 
neighboring  mines.  They  get  wider  apart  to  the  north.  In  the 
Carlisle  they  are  divided  by  40  feet  of  country,  while  southward 
they  approach  each  other,  and  in  the  Victory  and  Pandora  Com- 
pany's ground  they  are  seen  to  cross.  I  saw  a  section  of  the  upper 
workings  of  the  Pandora  in  which  these  same  faults  are  readily 
recognizable,  though  they  had  been  misinterpreted  by  the  draughts- 
man. In  Figs.  52  and  53  are  given  two  comparative  sections.  Fig. 
52  is  a  sketch  reproducing  on  a  smaller  scale  the  old  drawing  to  be 
seen  in  the  office  of  the  company.  Fig.  53  indicates  what  appears 
to  me  to  be  the  real  situation.  In  Fig.  52  S  is  called  the  leader, 
G  the  cap  of  the  saddle,  H  the  west  leg,  and  K  the  east  leg  of 
another  more  complete  formation.  The  lava  dike  follows  a  slide 
which  has  an  irregular  course'  through  the  two  bodies  of  quartz. 
Just  below  the  234-feet  cross-cut  the  legs  are  bent. 

Compare  this  with  the  section  of  the  Unity.  The  two  mines  ad- 
join, and  we  know  that  southward  the  two  faults  or  slides  are  ap- 


THE   BEXDIGO   GOLD-FIELD. 


59 


60  THE    BENDIGO   GOLD-FIELD. 

preaching  each  other.  Now  refer  to  Fig.  53,  where  G  is  the  cap  of 
a  formation,  which,  like  that  of  the  Unity,  of  which  it  is  undoubt- 
edly an  extension,  has  no  east  leg,  while  the  west  leg,  H,  is  faulted 
by  the  two  slides,  A,  B  and  C,  D.  In  the  Unity  we  saw  that 
the  lower  fault  was  flatter  than  the  other — it  is  so  here,  where 
they  cross.  Below  the  234-feet  cross-cut  we  have  a  partial  dis- 
location due  to  the  fault,  E,  F,  similar  to  that  seen  at  M  in  the 
Unity  (Fig.  45).  The  portion,  N,  of  the  formation  corresponds 
to  that  shown  at  C  in  the  Unity  section,  while  the  quartz  which 
accompanies  the  dike  at  L,  L  is  similar  to  that  which  usually 
follows  the  line  of  the  fault,  as  indicated  in  Figs.  47  and  48. 

The  question  arises,  which  way  was  the  movement  ?  The  only 
evidence  in  reply  is  that  obtained  by  noting  which  part  of  the 
country-rock  is  most  shattered.  In  the  Unity  the  country  between 
the  faults  has  been  fissured,  that  west  of  them  less,  and  that  east  of 
them  more.  That  the  west  country  has  not  been  subjected  to  much 
movement  is  shown  by  the  regularity  of  the  formation  in  the  451- 
feet  cross-cut.  It  seems  to  me,  therefore,  that  the  movement  was  an 
upward  one  on  the  part  of  the  country  east  of  the  first  fault,  accom- 
panied by  a  lesser  movement  in  the  same  direction  by  that  which 
lay  between  the  two  faults,  decreasing  westward  until  at  M  it  had 
almost  died  out. 

OTHER  INDICATIONS  OF  STRUCTURE. 

Having  given  a  description  of  some  of  the  typical  mines  of  the 
district,  it  remains  for  me  to  add  such  other  evidence  gathered  in  the 
various  mines  as  bears  most  directly  upon  the  structural  relations  of 
the  ore-deposits. 

Of  the  evidence  offered  by  the  underground  workings,  none  is 
more  beautiful  than  the  ripple-marking  at  the  Johnson's  mine.  This 
is  spen  at  its  best  in  the  1065-feet  north  level.  Figs.  54  and  55,  are 
sketches  made  underground  to  illustrate  it.* 

Fig.  54  was  taken  5  feet  north  of  Fig.  55.  The  crests  of  the 
waves  are  3  to  3J  inches  apart,  the  rock  in  which  they  occur  is  a 
very  hard  sandstone,  shading  into  a  quartzite,  and  forms  the  footwall 
of  the  reefs.  On  breaking  the  face  the  markings  cannot  be  followed 
into  the  next  layer  of  sandstone,  this  being  due  to  the  metamorphism 
which  the  rock  has  undergone,  and  its  cementation  along  the  lines 

*  It  requires  photography  to  do  justice  to  this  very  interesting  occurrence.  All 
I  can  do  is  to  give  roughly  an  idea  of  this  striking  evidence  of  the  bedded  character 
of  the  reefs. 


THE    BEXDIGO   GOLD-FIELD. 


61 


of  original  deposition.  The  preservation  of  the  ripple-marks  is  due 
to  the  fact  that  the  sandstone  face  which  shows  them  was  overlain 
by  a  soft  slate,  which  has  since  in  part  been  replaced  by  the  quartz 
of  the  lode.  The  markings  can  be  followed  for  100  feet  in  height, 
and  for  more  than  200  feet  in  length.  The  reef  of  which  this  is  the 
foot-wall  dips  east  about  70°  ;  it  was  in  this  part  of  the  mine  richly 
gold-bearing,  and  it  was  found  in  breaking  the  quartz*  that  it 
broke  with  difficulty,  owing  to  the  resistance  offered  by  the  pro- 
jections of  the  corrugations  which  were  so  striking  a  feature  of  the 
stopes.f 

Fig.  Gl. 


CONTORTIONS   IN   SANDSTONE. 

LAZARUS. 125O  LEVEL 

%  NATURAL   SIZE. 

These  ripple-markings  were  in  east  country.  At  the  550-feet  plat 
in  the  latter  mine,  immediately  behind  the  "west  reef,"  there  is  a 

f  The  ripple-marked  wall  formed  "the  shooting-wall,"  that  is,  it  was  utilized  in 
blasting  as  the  Hue  along  which  the  quartz  detached  itself  most  readily. 

|  Soon  after  my  third  visit  to  Sandhurst,  I  saw  an  almost  exact  duplication  of 
these  markings  in  the  sands  of  to-day.  It  was  in  New  Zealand.  We  were  trawling 
by  moonlight ;  and  while  pulling  in  the  net  I  noticed  that  the  sand  forming  the  bot- 
tom of  the  shallow  water  in  which  we  stood  was  covered  by  a  series  of  ripple-marks, 
whose  distance  apart  and  little  irregularities  resembled  those  which  I  had  seen  in 
the  Johnson's  mine ;  but  these  on  which  I  stood  were  of  to-day,  those  were  laid 
down  in  the  estuaries  of  the  Silurian  seas  ;  these  were  soft  and  yielding,  while  those 
had  been  consolidated  into  a  quartzhic  sandstone,  now  one  thousand,  and  at  one 
time  manv  thousand  feet  below  the  surface. 


62  THE   BENDIGO    GOLD-FIELD. 

bed  of  sandstone  whose  under  side  shows  a  cast  of  ripple-markings, 
in  other  words  instead  of  getting  ridges,  you  get  hollows,  the  true 
ripples  on  the  underlying  bed  are  not  to  be  seen,  but  the  sandstone 
which  was  deposited  upon  it  still  retains  the  impression,  the  nega- 
tive of  the  face  of  sand  which  it  overspread. 

At  the  Lazarus  mine  is  found  the  formation  shown  in  Figs.  56  to 
61,  reproduced  from  sketches  taken  in  some  old  stopes  at  the  bottom 
of  a  winze  leading  from  the  1250-feet  east  level.  Fig.  56  gives  a 
general  view  of  the  saddle.  A  A  is  the  cap,  which  is  not  at  all 
regular  in  outline,  and  both  above  and  below  breaks  up  into  spurs. 
The  east  leg  is  cut  off  by  a  fault,  on  which  the  winze  was  sunk. 
The  manager  informed  me  (the  ground  is  filled  up  now),  that  in 
stoping  it,  was  found  that  the  west  leg  also  was  cut  off  by  this  same 
"slide." 

The  remarkable  feature  of  this  formation  is  the  development  of 
radial  cleavage.  In  the  drawing,  a  a  are  lines  of  cleavage,  b  b  are 
structural  lines  parallel  to  the  bedding.  The  bedding  is  for  the 
most  part  completely  obliterated  by  the  cleavage.  On  careful  search 
the  lines  of  original  deposition  can  be  traced,  but  with  difficulty  and 
only  partially.  The  [most  striking  evidence,  however,  is  that  of 
some  extremely  delicate  but  distinct  markings  found  in  the  sand- 
stone underneath  the  arch  of  the  saddle,  markings  which  prove  in 
miniature  the  contortion  to  which  the  rock  has  been  subjected.  They 
are  shown  in  their  natural  size  in  Fig.  61,*  and  their  position  as 
regards  the  saddle  is  indicated  by  X  in  Fig.  56.  The  rock  in  which 
they  occur  is  a  very  fine-grained  sandstone,  the  contortions  being 
rendered  distinct  by  the  alternation  of  dark-  and  light-gray  laminse. 

Fig.  57  was  taken  in  the  winze.  The  slide  S  is  5  feet  wide,  and 
the  slaty  materials  of  which  it  is  composed  are  arranged  parallel  to 
the  bounding  walls.  A  small  quartz-seam  B  is  faulted,f  the  throw 
being  about  four  inches.  It  is  accompanied  by  a  narrow  band  of 
black  slaty  filling.  The  edges  of  the  beds  of  the  country  are  bent 
and  broken  at  their  contact  with  the  walls  of  the  "slide" — at  D. 

Fig  58  is  taken  in  center-country,  under  the  saddle.  A  is  a  vein 
of  quartz,  a  spur,  filling  one  of  the  many  fractures  produced  in  the 
bending  of  the  beds;  a  a  are  lines  of  cleavage,  at  this  point  very 
marked;  b  b  are  quartz-seams  arranged  along  the  structural  lines, 

*  This  might  be  taken  as  the  cross-section  of  a  mountain  range ;  and  certainly 
these  foldings,  though  only  covering  a  few  inches,  are  typical  of  the  plication  which 
has  produced  mountain  ranges. 

f  A  fault  within  a  fault. 


THE    BENPIGO   GOLD-FIELD. 


63 


which  are  parallel  to  the  bedding.  This  may  be  called  "  secret  bed- 
ding," since  the  fractures  are  doubtless  in  sympathy  with  the  bedding 
and  along  lines  of  original  deposition,  only  now  made  visible  by  the 
fissuring  through  which  relief  was  obtained  at  the  time  of  the  plica- 
tion of  the  rocks. 

Fig.  59  is  in  east-country,  just  above  the  slide  or  fault.  C  is 
slate ;  D,  slaty  sandstone ;  E,  sandstone.  A  and  B  are  quartz-spurs 
thrown  off  by  the  east  leg.  At  F  the  cleavage  is  twisted. 

This  formation,  the  several  portions  of  which  have  been  briefly 
described,  throws  a  good  deal  of  light  upon  the  structure  character- 
istic of  saddle-reefs. 

Evidence  of  the  structure  of  the  district  can  be  obtained  without 

Fig.  62. 


going  underground,  since  large  open  cuts  are  numerous  along  the 
main  lines  of  reef.  Several  sketches  made  in  the  surface-excava- 
tions are  shown  in  Figs.  62  to  66,  inclusive.  Figs.  62  and  63  were 
both  taken  behind  the  engine-house  of  the  "  180"  mine  on  Victoria 
Hill.  Fig.  63  shows  where  the  quartz  has  been  for  the  most  part 
removed,  leaving  an  arch  overhead.  C  is  debris;  D,  slaty  sand- 
stone; while  A  is  a  lava  dike,  the  same  dike  which  is  repeatedly 
seen  underground  and  which  forms  one  of  the  most  striking  features 
of  the  deepest  workings,  as  shown  in  Fig.  14. 

Fig.  62  is  about  100  yards  south  of  Fig.  63,  and  shows  the 
southern  continuation  of  the  same  anticline.  At  B,  the  bedding  is 
very  distinctly  to  the  west,  the  rock  being  "corduroy,"  which 
weathers  very  slowly.  The  country  about  the  apex  of  the  saddle 


64  THE    BENDIGO   GOLD-FIELD. 

has  undergone  considerable  alteration,  and  only  traces  of  the  original 
bedding  are  now  to  be  seen. 

Fig.  64  is  taken  in  the  vicinity  of  the  New  Red,  White  and  Blue 
mine.  The  saddle  is  very  sharp  and  distinct.  C  is  an  old  drift, 
while  D  consists  of  material  which  has  been  filled  in. 

Figs.  65  and  66  will  appear  curious.  They  are  sections  of  the 
same  anticline,  taken  from  the  opposite  sides  of  a  narrow  cutting. 
The  space  covered  is  only  7  to  8  feet  in  width.*  The  wavy  lines 
are  marked  by  small  seams  of  quartz  which  follow  the  contorted 
bedding  in  the  country-rock.  The  nearly  vertical  veins  are  inter- 
esting as  indicating  the  fractures  which  took  place  along  the  axis  of 
the  fold. 

This  closes  the  evidence  which  I  offer  as  bearing  most  directly 
upon  the  structural  relations  of  these  very  remarkable  ore-deposits 
of  Sandhurst.  Out  of  the  large  number  of  notes  and  sketches  made 
by  me  while  underground,  I  have  endeavored  to  place  before  the 
Institute  those  which  seemed  most  directly  pertinent.  Instances  in 
which  geology,  particularly  structural  geology,  and  practical  mining 
are  so  closely  allied  can  rarely  be  found.  The  close  relation  which 
they  bear  to  one  another  is  hardly  understood  by  the  busy  under- 
ground managers  of  the  mines,  save  in  a  few  very  noteworthy  cases ; 
and  this  is  scarcely  to  be  wondered  at,  seeing  that  almost  without 
exception  the  references  to  and  the  descriptions  of  the  Sandhurst 
mines,  meager  as  they  are,  on  the  part  of  geologists,  engineers, 
etc.,  are  quite  incorrect;  their  authors  having  confounded  the  bed- 
ding with  the  cleavage.  Misled  by  the  cleavage,  "its  mysteriously 
deceptive  harmonies  with  the  stratification  "f  on  tne  east  side  of  the 
saddles,  and  its  often  complete  obliteration  of  the  bedding  on  the 
west  side,  they  have  considered  that  the  east  leg  did  conform  to  the 
bedding,  but  that  the  western  cut  across  it,  that  is,  the  ore-deposits 
were  "  saddles  "  in  name  only. 

There  is  one  noteworthy  exception,  namely,  a  short  note  which 
appeared  in  the  quarterly  report  of  the  Mining  Department  of  Vic- 
toria, for  December,  1888,  by  E.  T.  Dunn,  formerly  government 
geologist  of  the  Cape  Colony.  In  that  note  attention  is  directed  to 

*  There  are  several  large  open  cuts  behind  the  Victoria  quartz  mine,  and  having 
noticed  that  in  different  parts  of  the  workings  the  country  dipped  east  and  west,  I 
hunted  for  the  turn-over  of  the  saddle.  It  was  only  a  ter  a  second  search  that,  in 
leaving  the  old  excavations  by  a  narrow  road-cutting,  I  found  what  is  represented 
iu  ray  sketches.  Recent  rain  had  rendered  the  structure  beautifully  distinct. 

f  Ruskin,  in  Schisma  Montium,  Deucalion. 


THE   BEXDIGO   GOLD-FIELD. 


65 


this  point.  Had  it  come  under  my  notice  previous  to  going  to 
Sandhurst,  I  should  have  been  spared  much  of  the  difficulty  which 
I  experienced  before  the  true  nature  of  the  deposits  became  manifest.* 

That  the  typical  ore-deposit  of  the  Sandhurst  gold-field  is  a  true 
anticline  there  can  be  no  doubt.  As  already  pointed  out,  the  saddle 
is  not  the  only  formation  in  which  the  gold-quartz  is  formed,  since 
the  spurs,  backs,  lodes,  etc.,  have  at  all  times  been  responsible  for  a 
very  large  share  of  the  output;  but  the  saddle  is  the  distinctive 
form  to  which  the  others  are  for  the  most  part  accessory  and  sub- 
sidiary. 

The  ripple-marks  frequently  observed   underground  are  incon- 


Fig.  63. 


trovertible  evidence  of  the  original  position  of  the  beds.  That,  for 
instance,  the  east  leg  of  the  big  saddle  in  the  Johnson's  follows  the 
true  line  of  stratification,  is  amply  proved  by  the  very  beautiful 
markings  seen  in  the  1060-feet  level.  Similarly,  ripple-marks  are 
seen  on  the  faces  of  beds  dipping  west.  Other  no  less  conclusive 
though  less  striking  evidence  has  been  given  in  the  descriptions  of 
the  various  mines. 

Mining  is  a  commercial  business  and  not  a  scientific  pursuit.    The 
le  on  its  dip  ceases  whenever  the  quartz  which  it 


following  of  a 


*  In  visiting  Sandhurst  one  usually  visits  first  the  more  famous  mines  on  Victoria 
Hilt,  such  as  the  celebrated  *'  180"  mine  and  others  near  it.  It  so  happens  that  in 
these  mines  that  the  structure  of  the  country-rock  is  most  hidden,  because  the 
cleavage  is  most  highly  developed.  The  smaller  mines  at  the  other  end  of  the  field 
show  the  true  character  of  the  ore-deposits  far  more  clearly.  Among  the  latter  the 
South  Xew  Chum  has  been  described  here. 

5 


66  THE   BENDIGO   GOLD-FIELD. 

contains  is  no  longer  auriferous;  and  as  a  consequence  the  mine- 
workings  rarely  disclose  the  ultimate  limits  of  the  lower  portions 
of  a  saddle-formation.  Lower  cross-cuts  will  intercept  a  thin  but 
pronounced  parting  in  the  country, a  "back"  which  could  be  traced 
upward  until  it  formed  the  boundary  of  a  big  lode  or  "reef;'7  or 
they  may  cut  through  a  "spur,"  which  if  followed  would  be  found 
to  lose  itself  in  an  east  or  west  leg,  the  distinction  in  the  two  cases 
being  solely  that  of  conformity  with  the  bedding  of  the  country- 
rock.  Where  the  legs,  as  parts  of  a  saddle-formation,  end,  and 
where  they  become  one  or  other  of  the  various  types  of  cross-fissure, 
no  man  can  say.  It  may  be  considered  that  whenever  they  lose 
their  true  character  as  bedded  veins  they  cease  to  be  the  lower  por- 
tions of  a  saddle;  but  the  distinction  is  theoretical  and  arbitrary; 
for  the  gold  knows  no  difference  and  is  found  in  both. 

The  same  system  of  fracturing  may  produce  in  one  part  of  the 
mine  a  "  big  reef,"  a  leg  of  a  saddle  which  is  highly  auriferous,  while 
overhead*  in  another  part  it  may  be  a  mere  fissure,  carrying  no 
quartz,  and  lined  only  with  a  thin  seam  of  black  clay,  which  cuts 
across  the  country  overlying  the  saddle.  Again  at  a  lower  depth, 
while  still  retaining  its  characteristics  as  a  portion  of  a  saddle,  it 
may  carry  quartz  which  is  not  sufficiently  gold-bearing  to  work,  or 
it  may  slowly  degenerate  into  a  "  leader,"  if  the  quartz  continue,  or 
a  "back7'  whenever  that  has  ceased,  becoming  nothing  more  than  a 
parting  between  a  bed  of  sandstone  and  a  bed  of  slate.  Again,  it 
may  eventually  cross  the  bedding,  cease  to  be  a  true  "  leg,"  and 
become  a  gold-bearing  "spur" ;  and  finally  it  may  be  traced  into  a 
mere  thread  of  white  quartz,  one  of  many,  traversing  a  bed  of  sand- 
stone. 

To  make  nice  distinctions  would  be  arbitrary  and  out  of  accord 
with  the  facts;  the  same  fissure  in  one  mine  plays  many  parts. 

While,  therefore,  I  would  not  say  that  the  legs  of  a  saddle-forma- 
tion never  go  astray  from  their  correct  course  between  the  bedding 
planes,  such  an  occurrence  would  be  found  only  when  they  are  begin- 
ning to  die  out,  and  does  in  no  way  modify  our  view  of  the  true  nature 
of  the  "saddle-reef,"  which,  notwithstanding  interesting  local  varia- 
tions of  structure,  is  a  distinct  type  of  ore-deposit — essentially  travers- 
ing the  Silurian  slates  and  sandstones  in  conformity  with  the  bed- 
ding, and  forming  along  the  anticlinal  undulations  of  the  enclosing 
country  those  bodies  of  gold-bearing  quartz  which  are  the  most  pecu- 

*  See  Fig  21,  where  an  instance  of  this  kind  is  shown  in  the  South  New  Chum. 


THE   BENDIGO   GOLD-FIELD. 


67 


liar  feature  of  the  mining  industry  and  the  most  valuable  depository 
of  the  wealth  of  the  Bendigo  gold-field. 

MINE-MANAGEMENT. 

Fig.  67  is  a  view  of  the  New  Chum  line  of  reef  from  Eaglehawk, 
copied  from  the  quarterly  mining  report  of  the  Victorian  govern- 
ment. 

There  are  at  present  engaged  in  the  exploitation  of  the  mines  143 
companies  and  21  tribute-parties,  the  former  including  four  private 
mines.  The  gold-field  has  been  developed  by  the  energy  of  its  own 
people,  the  amount  of  outside — chiefly  Melbourne — money  invested 
being  comparatively  small.  Sandhurst  has  profited  greatly  by  the 
enterprise  and  success  of  one  or  two  mine-owners,  such  as  the  late 
I.  B  Watson  and  the  present  owner  of  the  "  180  "  mine ;  but  its 
development  has  been  retarded,  on  the  other  hand,  by  the  prevalence 

Fig.  64. 


of  one  of  the  worst  systems  of  company-financiering.  The  actual 
management  of  the  mines,  both  above  and  under  ground,  is  in  the 
hands  of  capable  and  careful  men ;  but  they  are  hampered  by  the 
fact  that  reserve  capital  is  almost  unknown.  Of  the  28  dividend- 
paying  companies  of  1890,  four  appear  also  on  the  call  list.  That 
is  to  say,  these  four  companies  both  levied  calls  and  disbursed  divi- 
dends during  the  year.  A  series  of  fortnightly  sixpenny  dividends 
may  be  followed  by  a  number  of  fortnightly  calls,  supplemented 
by  a  bank-overdraft — a  state  of  affairs  which  may  swell  the  volume 
of  business  and  keep  a  number  of  clerks  employed,  but  which,  to 
say  the  least,  is  quite  unbusinesslike  and  highly  prejudicial  to  the 
proper  development  of  mines  which  require  extensive  and  systematic 
exploration.  The  fortnightly  dividend  is  the  bane  of  Bendigo. 
Whenever  a  rich  saddle-formation  is  discovered,  all  haste  is  made  to 
open  it  up;  as  soon  as  the  cross-cuts  and  drifts  have  intersected  the 
ore,  stoping  is  at  once  commenced,  the  quartz  being  broken  away  as 


68  THE   BENDIGO   GOLD-FIELD. 

rapidly  as  possible,  while  all  development-work  is  for  the  time  prac- 
tically suspended.  The  results  of  a  few  crushings  enable  the  di- 
rectors to  pay  off  the  bank-overdraft  and  enter  upon  the  regular 
announcement  of  dividend  after  dividend,  at  intervals  of  a  week  if 
a  fortnight  seems  too  long  !  No  part  of  the  profit  is  laid  aside  as  a 
reserve-fund,  and,  as  a  consequence,  when  the  ore-body  is  worked 
out,  the  dividends  abruptly  cease,  and  the  bank-account  is  overdrawn 
to  pay  running  expenses,  until  it  is  necessary  to  call  upon  the  share- 
holders for  fresh  assessments.  This  foolish  round  of  alternating 
surplus  and  deficit,  of  squandering,  borrowing  and  taxing,  has  gone 
on  year  after  year,  notwithstanding  some  of  the  more  thoughtful 
managers  are  fully  aware  of  its  harmful  character.  The  result  may 
be  seen  in  the  cases  of  mines  which  divided  in  profits  a  few  years 
ago  sums  varying  from  £100,000  to  over  £250,000,  and  are  now 
almost  idle  for  want  of  funds  to  open  up  new  ground.  The  imme- 
diate distribution  of  profits  leads  to  a  continual  change  in  the  per- 
sonnel of  the  shareholders,  so  that  a  mine  when  poorest  maybe  owned 
by  men  who  had  no  share  in  the  property  when  it  was  most  produc- 
tive. Mining  is  thus  brought  down  to  the  level  of  mere  specula- 
tion— an  evil  not  unknown,  under  different  forms,  in  other  districts, 
and  certain  everywhere  to  cripple  the  legitimate  industry  of  mining. 
The  management  of  the  mines  is  controlled  by  the  directors,  the 
"  legal  manager  "  and  the  "  mine-manager."  Since,  as  a  rule,  these 
are  all  resident  in  the  vicinity,  and  exercise  more  or  less  direct  super- 
vision, it  is  largely  a  question  of  personal  influence  which  is  in  the 
ascendant.  A  mine-manager,  as  known  to  English  companies, 
that  is,  a  manager  of  all  the  mining  work,  or  a  superintendent,  as 
known  in  the  United  States,  is  not  found  in  this  gold-field.  The  re- 
sponsibility of  superintendence  is  much  scattered.  The  "  mine-man- 
ager" receives  the  pay  of  a  foreman — about  £20  or  $100  per  month. 
The  "  legal  manager  "  is  the  business  man  and  book-keeper.  The 
directors  control  the  policy  of  the  company,  and  also  do  much  of 
the  work  often  delegated  elsewhere  to  a  consulting  engineer.  Such 
a  thing  as  a  trained  mining  engineer  is  not  to  be  found  upon  the 
staff  of  any  of  the  companies ;  and  the  work  done,  as  a  conse- 
qence,  lacks  progressive  character.  The  actual  mining  work  under 
ground  leaves  nothing  to  be  desired.  It  is  carried  out  under  the  eyes 
of  men  whose  superiors  as  miners  cannot  be  found  ;  but  a  want  of 
system  is  to  be  observed  in  the  development  of  the  mines. 


THE   BEXDIGO   GOLD-FIELD. 


TREATMENT  OF  THE  ORE. 


69 


The  handling  of  the  ore  in  the  mills  is  far  from  satisfactory.  The 
explanation  is  simple.  Of  the  managers  of  27  mines  which  I  exam- 
ined, the  names  of  25  indicated  the  fact  that  they  hailed  from  the  west  of 
England,  while  the  other  two,  though  native-born,  were  of  the  same 
stock.  The  men  of  Doon  and  Cornwall  are  miners  second  to  none; 
but  they  make  the  most  unprogressive  of  mill-men. 

The  gold-ore  of  this  field  belongs  to  the  simplest  type  of  the  free- 
milling  class.  As  a  rule,  it  consists  of  white  quartz  carrying  a  very 
small  proportion  (from  0.25  to  1  per  cent.)  of  arsenical  pyrites.  Iron 
and  copper  pyrites,  blende  and  galena  are  also  frequently  present, 
but  in  very  inconsiderable  amount.  The  gold  varies  greatly  in 
its  mode  of  occurrence,  but  is  usually  coarse,  in  the  rich  ore 


Fig.  65. 


almost  invariably  visible,  and  of  uniformly  high  purity,  being 
worth  £3  17s.  Od.  to  £3  19s.  Od.  per  ounce — pure  gold  being  worth 
at  the  London  mint  £4  4s.  lljd. 

The  quartz  itself  is  usually  dead-white,  with  an  appearance 
which,  in  California,  would  be  considered  most  unfavorable  to  the 
presence  of  gold.  It  has  a  splintery  fracture,  rendering  it  easy 
to  break.  The  mill-stuff  consists  of  the  quartz  mixed  with  from 
one-third  to  over  one-half  of  vein-filling  and  country-rock,  which 
varies.  The  ratio  in  amount  of  slate  to  sandstone  and  the  con- 
sequent hardness  of  the  material  to  be  crushed  is  constantly 
changing.  It  is  the  fragments  of  excessively  hard  quarzitic  sand- 
stone which  cause  most  wear  and  tear  to  the  milling-machinery. 

Stamp-milling  of  the  simplest  kind  is  the  method  employed  to 
extract  the  gold.  The  mills  are  constructed  on  the  spot  by  excellent 


70  THE   BENDIGO   GOLD-FIELD. 

local  foundries,  at  a  price  usually  far  below  that  which  is  in  the 
western  United  States.  A  first-class  stamp-mill  of  40  heads,  engine 
and  shed  included,  with  shaking- tables  but  without  rock-breaker  or 
automatic  feeder,  can  be  contracted  for  at  from  £6000  to  £7000 
or  about  $30,000.  The  battery-frame  is  generally  of  iron. 
Whether  this  mode  of  construction  is  advantageous  to  the  work 
of  the  mill  is  open  to  doubt.  Both  the  breaking  and  the  feed- 
ing of  the  ore  is  done  by  hand,  and  in  this  respect  the  mills  of 
Sandhurst,  in  common  with  most  of  the  colonial  batteries,  are  a 
standing  disgrace  to  the  modern  mining  industry.  Inside  plates  are 
not  used.  Plain,  not  electro-silver-plated,  copper  plates  are  used  to 
arrest  the  gold  on  amalgamating  tables.  Blankets  precede  the  sha- 
king-tables, which  have  the  end-shock,*and  are -a  variation  of  the 
much-used  Rittinger  type- 

The  stamps  weigh  from  800  to  950  pounds  per  head ;  drop  8  to  9 
inches,  usually  70  to  75  times  per  minute,  and  crush,  as  a  rule,  about 
2  tons  per  head  per  24  hours.  The  depth  of  discharge  or  issue  va- 
ries widely,  but  the  average  is  about  3  to  3J  inches.  The  screen  or 
,  grating  is  made  of  slot-punched  Russia  iron,  having  120  to  180  holes 
per  square  inch.  The  bullion  is  from  940  to  960  fine. 

The  percentage  of  concentrates  varies  from  J  to  2  per  cent,  per 
ton  of  ore  milled.  These  are  treated  at  the  local  "  pyrites  works," 
of  which  there  are  several ;  the  method  of  extraction  varying  from 
arrastra  to  chlorination.  The  charge  is  generally  £3  per  load  of  25 
to  30  cwt. 

A  discussion  of  the  milling-practice  in  detail  and  from  a  technical 
standpoint  would  be  interesting  and  instructive ;  but  I  must  content 
myself  in  the  present  paper  with  the  above  indication  of  its  general 
character. 

GOVERNMENT  ASSISTANCE. 

The  serious  decline  in  the  output  of  gold  in  Victoria  has  led  to 
the  introduction  of  government  assistance  to  mining.  Whether  this 
course  has  done  good  or  harm  is  a  vexed  question.  In  the  hope  of 
giving  renewed  vigor  to  the  mining  of  the  colony,  the  Victorian  gov- 
ernment has  distributed  for  several  years  sums  amounting  to  £80,- 
000  per  annum,  the  intention  being  to  encourage  exploration.  A 
miner,  a  group  of  miners,  or  a  company  needing  funds  to  proceed 
with  a  cross-cut,  a  level  or  a  shaft  to  cut  a  known  lode,  or  to  explore 
for  a  suspected  one,  makes  application  before  a  local  committee, 
elected  by  the  miners,  and  called  the  Prospecting  Board.  This  body 


THE   BEXDIGO   GOLD-FIELD. 


71 


reports  it  favorably  or  otherwise  to  the  Secretary  for  Mines.  Out 
of  a  large  number  of  applications  submitted,  the  most  promising  and 
deserving  are  selected.  The  terms  of  the  grant  are  "  pound  for 
pound ;"  that  is,  for  a  grant,  say  of  £000,  there  must  be  another 
£500  furnished  by  the  applicants,  making  £1000  available  for  the 
particular  work  (and  that  only)  designated  in  the  application. 

Such  prospecting-grants  are  now  generally  condemned.  Beyond 
question  the  system  has  completely  failed  to  bring  about  fresh  dis- 
coveries by  prospecting.  I  have  seen  its  operation  in  different  parts 
of  the  colony,  particularly  in  the  mountainous  districts  which  have 
been,  as  yet,  least  prospected ;  and  the  result  appears  to  have  been 
only  to  pauperize  mining.  It  is  always  understood,  that  should  the 
subsidized  party  succeed  in  placing  the  assisted  mine  in  a  dividend- 


Fig.  66. 


paying  condition,  the  amount  of  the  grant  should  be  repaid  to  the 
government  from  the  first  profits.  This  has  been  done  in  instances 
so  few  as  to  be  remarkable. 

On  the  other  hand,  this  annual  dole  has  done  harm  by  encouraging 
that  improvidence,  whether  of  companies  or  of  individuals,  which  is 
the  chief  hindrance  to  systematic  mining.  It  has  long  been  a  bad 
feature  of  colonial  mining,  as  I  have  shown  above,  that  no  portion 
of  the  profits  is  put  aside  as  a  reserve  to  carry  on  the  work  of  devel- 
opment during  lean  years;  and  this  prospect  ing-grant  encourages 
that  evil.  Having  been  too  eager  for  dividends  to  provide  for  the 
time  when  the  reef  might "  pinch  out,"  the  mine-owners  fall  back 
upon  the  fatherly  assistance  of  a  benevolent  government.  Mining 
is  a  business  ;  and  if  a  mine  has  sound  prospects  of  success  it  is  very 
rarely  indeed  that  the  money  is  not  forthcoming  to  carry  on  the  work 
of  development.  The  money  thus  distributed  could  be  far  better 


72  THE    BENDiGO   GOLD-FIELD. 

employed  in  the  endowment  of  a  good  central  mining  school,  to  re- 
place the  second-rate  technical  institutions  which  at  present  usurp 
the  name. 

Prospecting  with  the  aid  of  the  diamond-drill  may  be  said  to  form 
a  part  of  the  scheme  of  governmental  assistance. 

During  the  past  year,  some  interesting  work  in  this  direction  has 
been  carried  out  at  Sandhurst.  At  the  invitation  of  Mr.  George 
Lansell,  who  offered  to  provide  the  necessary  compressed  air  and 
other  facilities,  the  Victorian  mining  department  decided,  toward 
the  end  of  1889,  to  put  down  a  series  of  bore-holes  from  the  bottom 
of  the  celebrated  "180"  mine,  which  had  then  reached  a  depth  of 
half  a  mile.  The  machine  used  was  Leschot's  patent,  manufactured 
in  San  Francisco,  the  core  being  1  inch  in  diameter.  Four  holes 
were  put  down,  having  an  aggregate  length  of  2335  feet.  The  record 
of  each  was  as  follows  : 

No.  1.  Bored  horizontally  eastward  from  a  point  in  the  1300-feet 
level  197  feet  east  of  the  shaft.  Length,  683  feet.  Commenced 
January  16,  and  finished  March  17, 1890.  Alternating  beds  of  slate 
and  sandstone  were  intersected  with  occasional  thin  seams  of  quartz. 
No  information  of  any  value  was  obtained,  and.  the  drilling  was 
stopped  by  a  strong  flow  of  water,  preventing  the  sufficiently  rapid 
removal  of  the  sediment  from  the  bit. 

No.  2.  Bored  downward  to  a  depth  of  453  feet,  with  an  inclina- 
tion of  9  inches  in  16  feet,  from  center-country  in  the  2600-feet 
cross-cut.  The  ground  varied  greatly  in  hardness,  and  finally  be- 
came broken  up,  when  water,  having  a  temperature  of  97°  F.,  and 
under  a  pressure  of  110  pounds  per  square  inch,  was  struck.* 

*  While  the  diamond-drill  was  at  work,  a  good  deal  of  notice  was  drawn  to  the 
heat  of  the  water  encountered  in  boring  at  the  bottom  of  the  "180"  mine.  The 
thermometer  showed  an  average  of  97°  F.,  and  at  one  time  a  maximum  of  107°  was 
reached,  as  recorded  by  three  instruments.  This  was  at  a  depth  of  450  feet  below 
the  2600-feet  level  or  3050  from  surface.  This  temperature  is  by  no  means  sur- 
prisingly high.  The  average  annual  mean  temperature  at  Sandhurst  is  60.2°  F., 
and  allowing  for  an  increment  of  1°  for  every  55  feet,  we  should  expect  at  450  feet 
a  temperature  of  about  115°  F,  which  agrees  fairly  well  with  the  facts  as  disclosed 
in  the  "180"  mine.  However,  the  matter  was  considered  of  sufficient  interest  to 
induce  a  thorough  examination  by  the  government  analyst,  Cosmo  Newberry,  of  the 
contents  of  the  water  so  obtained.  To  this  end,  two  and  a  half  tons  of  the  water  was 
evaporated  down  to  10  gallons,  care  being  taken  to  keep  out  impurities,  and  3125 
grains  of  solid  matter  remained,  mostly  carbonate  of  iron.  Assays  were  made,  but 
no  gold  was  obtained,  though  a  trace  of  a  metal  of  the  platinum  group  was  given  by 
the  precipitated  material.  The  results  were  disappointing,  in  failing  to  throw  light 
on  the  occurrence  of  the  gold  in  the  quartz  formation.  The  annual  mining  report 
of  the  department  says  that  a  further  (optical)  examination  is  to  be  made. 


THE    BEXDIGO   GOLD-FIELD. 


73 


74  THE   BENDIGO   GOLD-FIELD. 

No.  3.  Bored  at  a  slight  inclination  below  horizontal  for  636  feet 
westward  from  the  plat  at  the  2500-feet  level.  It  intercepted  several 
veins  of  quartz,  the  largest  of  which,  however,  was  only  9  inches 
thick. 

No.  4.  Bored  nearly  vertical  (inclining  only  slightly  to  the  west) 
at  a  point  30  feet  west  of  No.  2,  in  the  2600-feet  cross-cut,  to  the 
depth  of  562  feet  below  the  level,  or  3162  feet  below  the  surface. 
It  passed  through  about  200  feet  of  sandstone,  as  well  as  several 
beds  of  quartzitic  sandstone,  and  cuts  several  series  of  small  quartz- 
veins.  Hot  water  under  considerable  pressure  interfered  with  prog- 
ress, as  in  the  case  of  No.  2,  though  the  temperature  in  this  instance 
was  lower. 

The  result  of  these  borings  was  practically  nil.  No  discoveries 
of  importance  were  made;  and  it  is  doubtful  whether  the  drilling 
had  even  a  negative  value  in  proving  the  absence  of  auriferous 
quartz  in  that  portion  of  the  country  which  it  was  attempted  to  test. 
If  relied  upon  as  a  prospecting  instrument  under  such  conditions,  the 
diamond-drill  is  likely  to  do  serious  harm  by  causing  the  condem- 
nation of  large  areas  of  what  may  be  good  mining  ground.  In 
strata  possessing  regularity  and  continuity,  such  as  the  coal-seams; 
in  the  determination  of  the  thickness,  of  certain  beds  overlying 
known  deposits,  such  as  the  sheets  of  basalt  over  the  "deep  leads" 
of  California ;  in  the  tapping  of  old  workings  which  are  under  water ; 
in  the  measurement  of  large  ore-bodies  (as  was  done  in  the  case  of 
the  great  bonanza  at  Virginia  City);  and  in  many  other  instances, 
no  doubt,  the  diamond-drill,  if  judiciously  employed,  is  a  most  use- 
ful aid  to  the  miner;  but  in  quartz-mining  in  general,. and  in  such 
districts  as  Bendigo  in  particular,  it  is  often  likely  to  do  irretrieva- 
ble harm  by  fostering  delusive  hopes  on  one  hand  or  unnecessary 
discouragement  on  the  other. 

To  support  this  view,  it  is  not  necessary  to  go  outside  Victoria. 
In  the  discovery  of  gold-seams  and  the  exploration  of  deep  beds  of 
auriferous  alluvium,  the  diamond-drill,  under  the  judicious  direction 
of  the  government  geologist,  has  been  very  successful  ;  but  it  has 
proved  a  very  mixed  and  doubtful  blessing  indeed  to  quartz-mining. 
In  the  Sandhurst  district,  the  peculiar  structure  of  the  "saddle- 
reefs,"  and  the  comparatively  short  extent  of  most  of  the  bodies  of 
gold-bearing  quartz,  are  extremely  unfavorable  for  tests  of  this 
character.  This  is  particularly  true  of  horizontal  holes,  which 
might  penetrate  the  immediate  neighborhood  of  rich  formations 
without  discovering  them.  If  the  drill  is  to  be  used  at  all,  the 


THE   BENDIGO   GOLD-FIELD. 


75 


dangers  attendant  upon  its  use  should  be  minimized  by  planning  a 
series  of  holes  close  together,  so  as  to  test  thoroughly  and  satisfac- 
torily, at  least  a  small  portion  of  ground. 

DIMENSIONS  OF  CLAIMS. 

Among  the  interesting  features  of  this  gold-field  is  the  small  area 
of  the  claims.  The  following  table  gives  the  areas  of  eleven  con- 
tiguous properties  on  the  New  Chum  "  line  of  reef."  The  claims 
are  of  very  irregular  shape  (see  Fig.  7),  and  in  some  cases  the 
length  of  the  tract  is  much  greater  than  the  figures  given,  but  for 
purposes  of  comparison  the  measurement  is  taken  along  the  sup- 
posed line  of  the  New  Chum  reef. 

Areas  and  Depths  of  a  Group  of  Mines,  Victoria  Hill,  Bendigo. 


NAME  OF  MINE. 

Area  of  the 
Property. 

Length  along 
ftrike 
of  reef. 

Depth  of 
Shaft, 

Ironbark  Quartz  

Acres  R.     P. 
4     1     36 

Yards. 
220 

Feet. 
2140 

Victor!  a  Consol  s  

22    3    15 

259.6 

2162 

Gt.  Central  Victoria  

10    1     17 

250.8 

1970 

Victoria  Reef  Quartz 

7     0    25 

140.8 

2302 

Lansell's  "180"  

14     1     12 

171.6 

2641 

North  Old  Chum  

2    1     25 

88 

2310 

New  Chum  and  Victoria  

13    3     12 

710 

2300 

Old  Chum         

11     2    32 

710 

2208 

Lazarus  Co           .                       .           "i 

83.6) 

Lazarus  No  1           / 

22    1       7 

764.6  J 

2173 

Lansell's  "  222  " 

16    0    19 

994 

2100 

It  will  be  seen  that  the  average  area  of  each  property  is  but  a 
little  over  11  acres;  that  one  of  the  claims,  having  an  area  of  only 
two  acres,  has  workings  over  2-300  feet  deep ;  and  that  the  ten  shafts 
belonging  to  eleven  companies  have  an  average  depth  of  2230  feet, 
and  are  distributed  over  a  total  distance  of  less  than  a  mile  along 
the  strike  of  the  lode.  The  small  area  of  these  properties  is  prima- 
rily a  relic  of  the  early  days  when  the  claims  consisted  of  twenty 
yards  "along  the  line  of  reef"  for  two  men.  A  certain  amount  of 
consolidation  followed  on  the  initiation  of  deep  mining;  but  this  was 
limited  to  the  immediate  needs  of  the  time,  and  has  long  since  been 


76  THE    BENDIGO   GOLD-FIELD. 

outgrown  by  the  very  extensive  exploration  of  more  recent  years. 
A  circumstance  permitting  the  working  of  these  small  areas  is  the 
absence  of  any  large  quantity  of  water  in  the  mines.  In  the  par- 
ticular group  of  properties  cited  above  there  is  not  a  single  pump. 
The  little  water  that  finds  its  way  into  the  workings  is  raised  with 
tanks  alone.  At  the  "180,"  the  deepest  mine  in  Australia,  3000 
gallons  are  hoisted  per  24  hours. 

The  largest  areas  held  by  mining  companies  are  as  follows: 

« 

Acres.  Rods.  Perches. 

Hercules  and  Energetic, .85          3  17 

Johnson's  Reef, ."-./:-         .     71          2  21 

Catherine  Reef  United,  .        .    ^.'      .        .      '.       '.     65          3  12 

New  Red,  White  and  Blue  Cons 'V.     41          3  27 

Garden  Gully  United,  .        .        .        .        .        ...    41          3  0 

It  is  seen  that  even  the  largest  properties  are  of  a  size  which  would 
be  considered  small  in  many  districts.  It  must  be  admitted,  how- 
ever, that  the  holding  of  an  extensive  acreage  does  not,  in  Sand- 
hurst, necessarily  mean  extensive  explorations;  since,  by  reason  of 
the  want  of  working-capital,  most  of  the  companies  confine  their 
operations  to  such  portions  of  their  holdings  as  are  in  the  immediate 
vicinity  of  the  main  shaft.  This  bad  feature  of  the  mining  work 
will  be  slowly  overcome,  no  doubt,  by  further  consolidation.  The 
twin  Lazarus  Companies  have  set  a  good  example  by  sharing  one 
working-shaft;  and  a  recent  attempt  to  consolidate  the  North  Old 
Chum,  New  Chum,  and  Victoria,  though  unsuccessful,  may  be  taken 
as  an  indication  of  the  growth  of  a  proper  appreciation  of  the  neces- 
sity for  such  measures. 

DEEP  MINING. 

The  list  of  deep  mines  just  given  suggests  the  general  subject  of 
deep  sinking,  a  feature  of  mining  at  Sandhurst  to  which  reference  is 
often  made  in  the  colonies.  This  practice  owes  its  beginning  to  the 
"180"  mine*  When  the  mine  was  purchased  in  1873,  the  shaft 
was  only  400  feet  deep,  but  the  neighboring  North  Old  Chum,  New 
Chum,  and  Victoria,  Old  Chum,  and  Lazarus,  were  doing  well  on  a 
reef  which  traversed  the  mines  from  600  to  700  feet  below  the  sur- 
face. The  sinking  of  the  shaft  of  the  "  180  "  mine  was  commenced. 
At  about  600  feet  £120,000  of  gold  was  won.  Sinking  was  con- 
tinued in  the  face  of  much  ridicule,  and  slowly  the  mine  attained  a 
depth  which  in  those  days  was  considered  very  geat.  Much  money 
was  expended  without  any  return,  until,  in  1883,  after  ten  years  of 


THE   BEXDIGO   GOLD-FIELD.  77 

steady  development,  the  top  of  the  saddle  was  cut  in  the  1548-feet 
level.  An  ore-body  of  extraordinary  richness  was  uncovered,  and 
stoping  began ;  but  the  sinking  of  the  shaft  continued.  The  Mel- 
bourne Argus  of  that  day  said  :  "  The  success  of  this  venture  in  deep 
mining  decides  the  prosperity  of  Sandhurst  for  a  further  decade  at 
least."  The  mine  is  now  ^641  feet  deep.  The  success  of  deep 
prospecting  having  been  proved  in  this  trial-instance,  imitators  were 
not  wanting;  and  there  were  soon  several  mines  competing  for  the 
record  of  greatest  depth.  Deep  sinking  developed  into  a  craze 
which  seemed  at  one  time  likely  to  do  serious  injury  to  the  proper 
exploitation  of  the  mines.  The  result  is  seen  to-day  in  the  18 
shafts,  each  of  which  has  a  depth  of  over  2000  feet. 

Among  the  causes  of  this  state  of  things  the  structure  of  the  ore- 
deposits  may  be  named  first.  The  Bendigo  miner  has  an  embarrass 
de  richesse  in  the  matter  of  quartz- formation.  Should  a  saddle  be 
intercepted,  the  first  crushing  from  which  yields  scarcely  enough  gold 
to  pay  expenses,  it  is  soon  left  on  one  side  in  the  search  for  the  next 
formation,  which  is  usually  not  far  below.  Below,  not  ahead,  for, 
instead  of  longitudinal  extension,  the  miner  in  this  gold-field  looks 
for  a  vertical  repetition  of  the  auriferous  formations.  Did  each  mine 
uncover  one  lode  only,  there  would  be  more  extensive  and  patient 
prospecting  at  any  one  given  level ;  but,  as  matters  stand,  the  ex- 
ploration is  not  so  thorough  as  it  should  be,  for  the  reason  that  it  is 
divided  among  several  levels. 

The  most  potent  cause  is,  however,  seen  in  the  success  of  the  deep 
mines.  Deep  sinking  has  not  drawn  blanks  alone,  but  many  prizes, 
such  as  the  bonanzas  of  the  Great  Extended  Hustlers,  at  1800  feet ; 
the  New  Chum  Consolidated,  at  1810;  the  Shenandoah,  at  1900; 
the  Lazarus,  at  2000;  Lansell's  "  222,"  at  2000;  the  New  Chum 
Railway,  at  2025;  and  the  North  Old  Chum,  at  2290  feet.  As  I 
have  said,  there  are  1 8  shafts  over  2000  feet  in  depth.  They  belong  to 
20  companies,  there  being  two  instances — the  two  in  Shenandoah  and 
the  twin  Lazarus  companies — where  one  main  working-shaft  is  used 
in  common.  Out  of  these  20  companies,  7  are  upon  the  dividend- 
list;  or,  to  inquire  further,  4  are  working  quartz  which  is  highly 
auriferous  and  6  are  breaking  ore  which  is  yielding  profits,  while  of 
the  remaining  ten,  nine  are  in  that  process  of  prospecting  and  develop- 
ment which  here  succeeds  (though  it  ought  to  accompany)  a  period 
of  stoping,  and  one  is  idle.  This  is  a  record  above  the  average  of  even 
shallow  mining. 

The  actual  yield,  during  1890,  of  the  deepest-producing  mines  is 


78 


THE    BENDIGO    GOLD-FIELD. 


given  as  follows  in  the  quarterly  report  of  the  Victorian  Mining 
Department : 


NAME  OF  MINE. 

Quantity 
crushed. 

Yield. 

Average. 

Depth 
of 
Slopes. 

Depth 
of 
Shaft. 

Oz. 

Dwt. 

Gr. 

;oz. 

Dwt. 

Gr. 

Feet. 

Feet. 

Tons. 

Gt.  Extended  Hustlers... 
Lazarus  Company      

16,612 
6,232 
7,282 
3,454 
18,721 
9,797 
7,325 
7,474 
1,048 
2,496 
1,752 
3,117 

3,780 
5,059 
3,665 
2,510 
5,153 
2,243 
10,371 
5,039 
948 
1,446 
1,169 
1,183 

4 
0 
16 
2 

14 
10 
17 
3 
3 
19 
13 
13 

0 
0 
0 
0 
0 
0 
12 
0 
0 
21 
0 
0 

0 
0 
0 
0 
0 
0 

1 

0 
0 
0 
0 
0 

4 
16 
10 
14 
5 
4 
8 
13 
18 
11 
13 
7 

13 

• 

6 
1 
12 
12 
14 
8 
11 
2 
5 
8 
14 

1,800 
2,000 
2,000 
1,950 
1,800 
1,900 
2,025 
1,990 
1,990 
1,800 
2,290 
1,800 

2,040 
2,110 
2,110 
2,105 
1,850 
1,940 
2,078 
2,010 
2,010 
1,840 
2,310 
2,113 

Jjazarus  No  1 

Lansell's  "22°" 

New  Chum  Con  

New  Chum  United  

New  C^um  Railway 

North  Shenandoah  

Shamrock                

North  Old  Chum 

Totals     

85,310 

42,571 

5 

9 

23,345 
1,945 

24,516 
2,043 

Averages        

9 

23 

Leaving  on  one  side  numerous  small  lots  of  ore,  and  taking  into 
account  only  the  results  obtained  from  12  of  the  deepest  mines  which 
were  working  regularly,  it  is  found  that  during  the  year  these  dozen 
claims  yielded  85,310  tons  of  ore,  giving  42,571  ounces  or  an  aver- 
age of  10  pennyweights  per  ton,  the  average  depth  at  which  the  ore 
was  broken  being  1945  feet. 

All  but  one  of  these  mines  are  on  the  dividend-list.  We  must 
inquire  further  in  order  to  arrive  at  a  just  appreciation  of  the  signifi- 
cance of  this  analysis.  Of  these  12  mines,  11  are  paying  dividends 
on  ores  broken  at  an  average  depth  of  about  2000  feet.  There  are 
a  similar  number,  working  at  an  equal  average  depth,  which  are  not 
at  present  making  profits.  It  is  most  probable  that,  during  an  in- 
terval of  a  year  fully  a  third  of  the  former  will  step  into  the  ranks 
of  the  latter;  that  is  to  say,  they  will  cease  to  break  highly  aurifer- 
ous quartz  and  become  prospectors  for  a  new  run  of  ore-ground, 
while,  on  the  other  hand,  an  approximately  similar  number  will 
replace  them  from  the  list  of  mines  which  at  present  are  in  process 


THE   BENDIGO    GOLD-FIELD.  79 

of  development.  We  see,  then,  that  at  the  present  time  half  of  the 
mines  working  at  depths  between  1800  and  2600  feet  are  profit-pay- 
ing. The  average  yield  of  their  ore  is  10  dwt.,  while  that  of  the 
district  as  a  whole  is  9  dwt.  5  gr.  per  ton.  The  best  returns  at 
present  come  from  the  New  Chum  Railway,  which,  at  2025  feet 
depth,  is  breaking  quartz  averaging  nearly  J  J  ounces  per  ton.  Dur- 
ing the  year  this  mine  paid  dividends  amounting  to  £21,672  on  a 
paid-up  capital  of  £28,589  and  a  nominal  capital  of  £36,890.  Its 
total  dividends  to  date  have  been  £52,078. 

During  the  second  half-year  the  Shenandoah,  working  at  1990 
feet  depth,  produced  4555  tons  of  quartz,  yielding  3717  oz.  17  dwt., 
or  an  average  of  16  dwt.  per  ton.  Dividends  of  £8400  were  paid 
during  the  6  months,  on  a  called-up  capital  of  £12,800.  Altogether 
this  company  has  returned  £59,600  in  dividends. 

The  Lazarus  Company,  working  at  2000  feet,  on  76-dwt.  ore,  paid 
out  during  1890  dividends  of  £15,750  on  a  paid-up  capital  of  £63,- 
187.  The  total  dividends  of  this  mine  to  date  have  been  exactly  the 
full  amount  of  its  nominal  capital,  £67,500. 

The  results  obtained  in  some  cases  appear  to  leave  a  very  slight 
margin  of  profit.  The  average  of  the  Great  Extended  Hustlers,  the 
New  Chum  Tjnited,  and  the  New  Chum  Consolidated  mines  is  very 
low.  It  speaks  well  for  the  size  of  the  lodes  and  the  handling  of  the 
ore,  that  dividends  are  possible  at  a  depth  of  nearly  2000  feet  on  5- 
dwt.  mill-stuff.  The  New  Chum  Consolidated  is  an  instance  of  very 
successful  gold-mining.  The  return  of  5  dwt.  12  gr.  shown  in  the 
list  given  above  is  higher  than  the  ordinary  average  of  the  minef 
since  richer  quartz  than  usual  was  broken  in  the  second  half  year. 
For  the  year  ending  30th  June,  1890,  9586  tons  were  sent  up  from 
the  1800-foot  level,  yielding.  1722  oz.  19  dwt.  of  gold  at  the  mill 
and  278  oz.  8  dwt.  (from  106  loads)  at  the  pyrites  works.  The  total 
value  of  the  yield  was  £7943  5s.  9d.  The  average  of  the  ore  was 
3  dwt.  14  gr.  only,  but  this  gave  a  profit  of  £1510  6s.  9c/.,  equiva- 
lent to  a  shilling  dividend  on  each  of  the  28,000  shares.  The  yield 
was  16s.  9d.  (say  §4)  per  ton,  and  the  cost  13s.  5d.  (say  $2.70)  per 
ton.  Even  on  this  low  return  the  company,  having  a  paid-up  capi- 
tal of  only  £18,200,  was  working  at  a  profit  of  11  per  cent,  per  an- 
num. The  New  Chum  Consolidated  has  paid  £132,300  on  its 
nominal  capital  of  £42,000  and  its  oaid-up  capital  of  £18/200.  The 
other  mines  will  show  scarcely  less  striking  results  so  far  as  concerns 
the  ratio  of  money  returned  to  that  expended.* 

*  As  stated  in  the  first  part  of  this  paper,  out  of  the  28  dividend-paying  mines  of 


80  THE   BENDIGO   GOLD-FIELD. 

The  favorable  record  of  deep  mining  in  this  gold-field,  as  ont- 
lined  in  the  above  paragraphs,  has  led  many  to  quote  the  district  in 
proof  of  the  richness  of  the  deeper  portions  of  quartz  lodes.  This 
argument  ignores  the  unique  character  of  the  geological  structure  of 
the  district.  Bendigo  does  not  furnish  proof  of  the  continuance  of 
pay-ore  to  great  depths  in  ordinary  veins.  If  we  look  upon  each 
saddle-formation  as  a  distinct  lode  (which  it  no  doubt  is),  we  per- 
ceive that  the  vertical  extent  of  the  auriferous  quartz  is  very  limited. 
As  a  rule,  in  this  district,  a  "reef"  which  can  be  worked  to  profit 
in  three  levels  or  stoped  in  two  lifts  may  be  considered  above  the 
average.  The  different  saddles  form  distinct  lode- formations,  trav- 
ersing beds  of  the  country-rock  which  are  different  from  those  either 
above  or  below. 

PROSPECTING. 

It  is* the  fact  last  mentioned  which  necessitates  the  most  patient 
prospecting.  Systematic  development  is  always  one  of  the  most 
important  features  of  mine-work.  In  such  ore-deposits -as  these  it 
is  of  paramount  importance.  Owing  to  lack  of  reserve-capital,  and 
the  haste  made  to  sink  the  shafts  deeper,  there  has  not  been  that 
careful  and  patient  prospecting,  which  the  peculiar  structure  of  the 
district  demands,  of  the  ground  rendered  accessible  by  each  level. 

Several  of  the  richest  saddle-formations  have  passed  longitudi- 
nally through  a  succession  of  adjacent  claims.  Such  was  the  main 
Garden  Gully  saddle,  and  such  is  the  formation  now  so  successfully 
worked  from  the  New  Chum  Railway  to  the  "  180"  mine.  As  a 
rule,  however,  the  ore-shoots,  particularly  the  richest,  are  small  in 
extent,  and,  unless  the  ground  is  carefully  cut  up  by  drifts  and  cross- 
cuts, they  are  easily  missed.  Two  instances  will  illustrate  this.  In 
the  Old  Hustlers  mine,  after  the  workings  had  reached  a  depth  of 
over  1500  feet,  there  was  accidentally  found,  last  February,  a  good 
body  of  auriferous  quartz,  between  the  730-  and  830-foot  levels,  in 
ground  which  had  been  considered  thoroughly  tested.  In  the  Her- 
cules and  Energetic  mine  there  was  found,  in  December,  1889,  a 
body  of  quartz  8  feet  square,  which  gave  £9000  worth  of  gold,  46 
tons  yielding  at  the  rate  of  46-J  ounces  per  ton.  This  was  exposed 
in  making  a  connection  with  a  winzp,  and  was  as  unexpected  as  it 
was  valuable. 

1890,  I  obtained  the  results  given  by  20,  and  found  that  all  save  four  had  more  than 
returned  their  paid-up  capital.  The  average  of  the  20  showed  an  expenditure  of 
£31,167  per  mine  on  a  nominal  capital  of  £48,742  pe'r  mine. 


THE   BEOTIGO   GOLD-FIELD.  81 

At  present,  the  work  of  development  is  confined  almost  entirely 
to  the  three  great  "  lines  of  reef," — the  New  Chum,  the  Garden 
Gully,  and  the  Hustlers, — and  more  particularly  to  the  immediate 
vicinity  of  the  big  mines.  This  is  not  surprising.  New  mines  are 
opened  as  continuations  of  already  proved  properties,  and  there  is  a 
strong  tendency  to  remain  in  the  neighborhood  of  ground  which  is 
known  to  have  been  rich.  But  at  Sandhurst  this  has  been  overdone, 
and  the  result  is  that  the  north  and  south  extensions  of  the  main 
"  lines  of  reef  "  have  been  but  little  tested,  while  similarly  the  inter- 
mediate lodes  or  "side-lines"  have  been  much  neglected.  Since  it 
has  been  demonstrated  by  the  Geological  Survey,  as  well  as  by  actual 
mining,  that  the  gold-belt  continues  for  several  miles  on  either  side 
of  the  towns  of  Eaglehawk  and  Bendigo,  it  would  be  well  to  dis- 
tribute upon  shallow  ground,  which  is  as  yet  unworked,  a  little  of 
that  energy  and  capital  which  is  now  expended  on  deep  sinking ;  for 
here,  as  in  most  mining  districts,*  the  first  few  hundred  feet  are  gen- 
erally richer  than  any  succeeding  horizon. 

As  to  the  exploration  of  the  "  side-lines "  or  quartz  formations 
which  occur  between  the  main  anticlinal  axes,  attention  has  been 
drawn  to  these  portions  of  the  district  by  the  marked  success  of  the 
New  Red,  White,  and  Blue  Consolidated,  which  is  working  a  run 
of  rich  spurs  on  the  Sheepshead  lode  or  reef,  intermediate  between 
the  Garden  Gully  and  the  New  Chum.  In  this  connection  it  is  a 
curious  fact  that,  notwithstanding  the  system  of  government  assist- 
ance, no  cross-cut  has  been  driven  between  the  main  u  lines  of  reef" 
in  that  portion  of  the  district  (in  the  town  itself)  where  they  have 
been  proved  to  be  richest.  Such  an  exploration  is  recommended  by 
the  structure  of  the  country,  the  richness  of  this  section  of  the  gold- 
field,  and  the  experience  of  other  mining  districts. 

OUTLOOK  FOR  THE  FUTURE. 

The  prospect  of  future  deep  mining  on  this  gold-field  is  most 
encouraging.  The  depths  yet  reached  are  far  within  the  capabilities 


*  There  are  exceptions,  but  they  are  not  numerous.  I  recall  the  history  of  some 
of  the  mines  on  the  "Mother-lode"  in  Amador  county,  Cal.,  where  no  profitable 
returns  were  obtained  until  several  hundred  feet  had  been  sunk.  As  a  rule,  how- 
ever, the  increasing  richness  of  mines  with  depth  is  a  fal.lacy  too  often  found  among 
the  paragraphs  of  a  mine-report.  In  most  districts  there  are  few  gold-mines,  the 
first  50  to  200  feet  of  which  did  not  exceed  in  richness  any  succeeding  horizon. 

6 


82  THE    BENDIGO   GOLD-FIELD. 

of  modern  mining  machinery.*  There  is  no  reason  to  expect  any 
increase  of  water ;  on  the  contrary,  the  experience  of  deep  mining 
in  other  places  points  to  a  diminution  in  the  quantity  of  water  as 
depth  is  gained.  No  chemical  causes  have  been  observed  as  active 
in  this  district  which  would  tend  to  make  the  underground  temper- 
ature increase  other  than  with  the  usual  increment  of  1°  for  every 
50  or  60  feet  of  additional  depth.  Moreover,  there  is  every  proba- 
bility, from  a  geological  standpoint,  that  the  saddle-reef  formations 
will  be  repeated,  as  in  the  2000  feet  or  more  already  pierced  ;  for  the 
only  cause  likely  to  bring  them  to  an  end,  the  granite  contact,  is  at  a 
depth  far  beyond  human  reach.  The  cost  of  exploitation  will  in- 
crease with  depth,  but,  as  the  mines  are  comparatively  dry  and  the 
encasing  rock  does  not  become  harder,  it  need  not  be  expected  that 
this  increase  will  be  material  between  200$  and  3000  feet.f  Below 
3000  feet,  increased  power  and  efficiency  of  the  winding-engines,  for 
\yhich  there  is  yet  plenty  of  room  at  Sandhurst,  will  compensate  for 
the  increasing  distance  from  which  the  ore  will  be  lifted. 

At  present,  generally  speaking,  5  dwt.  of  gold  per  ton  will,  with  a 
3-feet  or  4- feet  reef,  pay  the  expenses  of  the  mine  and  mill.  The  New 
Chum  Consolidated  has  shown  how,  at  the  end  of  the  second  thousand 
feet  from  the  surface,  3J-dwt.  ore  may  be  made  to  pay.  The  width 
of  the  lode  in  the  New  Chum  Railway,  the  Shenandoah,  the  New 
Chum  Consolidated,  the  New  Chum  United,  etc.,  averages  about  6 
to  8  feet;  and  it  is  the  width  of  the  quartz  in  the  reefs  which  will 
determine  the  economical  results  of  its  extraction.  In  this  respect 
there  is  no  reason  to  foresee  a  diminution.  Nor  is  there  any  ap- 
parent reason  to  expect  a  decline  in  the  gold-contents  of  the  quartz. 
In  most  gold-mines  the  first  200  or  300  feet  are  richer  than  any  suc- 
ceeding horizon  of  similar  thickness;  but  having  once  passed  out  of 
the  region  of  surface-waters  there  is  nothing  to  cause  one  to  expect  a 
marked  change.  Poor  zones  and  rich  ones  will  alternate  as  hereto- 

*  The  shafts  are  invariably  vertical,  the  winding  being  done  by  steam-power  with 
round  wire-ropes  and  cages.  Double-decked  cages  are  not  in  use.  Under  the  gov- 
ernment regulations  and  the  supervision  of  the  mine-inspector,  the  winding-appa- 
ratus is  always  in  good  order,  and  the  safety-appliances  are  frequently  and  regularly 
tested. 

f  The  speed  of  sinking  varies.  The  country  traversed  by  the  New  Chum  lode 
is  less  hard  than  that  of  the  Garden  Gully ;  hence,  while  at  a  depth  of  over  2000 
feet  in  the  "  180  "  mine,  the  speed  of  sinking  the  last  200  feet  averaged  20  feet  per 
fortnight  (the  distance  from  2440  to  2640  feet  being  accomplished  in  exactly  ten 
fortnights) ;  the  average  rate  in  the  Victory  and  Pandora,  on  the  Garden  Gully 
line,  is  12o  feet  per  fortnight.  In  both  cases  timbering,  etc.,  is  included. 


THE    BENDIGO   GOLD-FIELD.  83 

fore ;  but,  owing  to  the  folding  of  the  country  in  which  the  reefs 
occur  and  the  recurrence  of  the  beds,  the  mine-workings  will,  at 
greater  depths,  pass  through  portions  of  country  already  met  with 
nearer  the  surface.  The  gold  does  not  appear  to  have  become  more 
refractory  with  increasing  distance  from  daylight ;  the  percentage  of 
pyrites  has  varied  but  little,  while  the  fineness  of  the  gold  has  not 
changed.* 

It  will  be  primarily  a  question  of  the  economical  handling  of  the 
ore,  and  in  this  respect  the  underground  exploitation  is  at  present  as 
good  as  the  treatment  at  the  surface  is  bad.  With  mills  of  enlarged 
capacity,  properly  equipped  with  modern  improvements  (particu- 
larly with  automatic  feeders  and  with  rock-breakers),  the  Bendigo 
gold-field  should  long  continue  to  be  the  home  of  successful  gold 
quartz-mining  and  the  pioneer  of  deep  sinking. 


NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors, 
or  communications  for  publication  as  "  Discussion/'  or  independent 
papers  on  the  same  or  a  related  subject,  are  earnestly  invited. 

*  In  the  Lazarus,  at  2000  feet,  I  saw  white  quartz  containing  beautiful  coarse 
gold  in  pieces  weighing  several  pennyweights.  The  gold  at  the  greatest  depths 
cached  is  still  22f  to  23  carats  or  945  to  960  fine. 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OP  MINING  ENGINEERS.] 


THE  BENDIGO  GOLD-FIELD  (SECOND  PAPER):  ORE- 
DEPOSITS  OTHER  THAN  SADDLES. 

BY  T.    A.    RICKARD,    DENVER,  COLORADO. 

(Schuylkill  Valley  Meeting,  Reading,  October,  1892.) 

THE  earlier  paper  (Trans.,  xx.,  463)  describing  this  Victorian 
mining  district,  to  which  the  present  is  supplementary,  was  mainly 
confined  to  the  consideration  of  the  "saddle-reefs,"  as  scientifically 
the  most  interesting  and  economically  the  most  important  of  the 
ore-deposits  of  Bendigo.  Incidentally,  however,  references  were 
also  made  to  other  gold-bearing  quartz-formations  worked  in  the 
district ;  and  of  these  a  brief  account  will  now  be  given.  Among 
them  the  most  productive  is  that  which  is  locally  named  a  "  make  of 
spurs"  or  "spur-formation,"  that  is,  a  network  of  quartz-veins 
bearing  some  resemblance  to  the  type  known  as  Stockwerk. 

THE  CATHEKINE  REEF  UXITED. 

This  mine,  situated  at  Eaglehawk,  is  a  representative  of  the  class 
characterized  by  this  form  of  ore-deposit.  The  underground  work- 
ings disclose  a  strikingly  regular  succession  of  alternating  slate  and 
sandstone  beds  with  easterly  dip.  The  different  members  of  the 
series  are  named  according  to  their  thickness,  which  in  any  one  bed 
varies  between  narrow  limits  only.  Fig.  1  is  a  cross-section,  illus- 
trating the  structure  of  that  portion  of  the  Lower  Silurian  country- 
rock  which  contains  most  of  the  mine-workings.  The  scale  of  the 
drawing  is  too  small,  and  it  would  otherwise  be  confusing,  to  indi- 
cate the  quartz-spurs  themselves;  but  it  will  be  understood  that  cer- 
tain members  of  this  series  of  slates  and  sandstones  are  traversed  by 
comparatively  small  and  generally  irregular  veins  of  quartz  called 
"  spurs,"  and  confined  either  to  one  bed  or  to  a  certain  succession  of 
beds. 

The  " ore-shoots"  of  the  mine  are  the  "runs"  or  "makes"  of 
spurs,  which  in  one  plane  (that  of  the  strike  of  the  enclosing  rock) 
pitch  north  22  inches  in  6  feet,  and  in  the  other  plane  ^that  of  its 
dip)  cross  the  bedding  of  the  country  nearly  at  right  angles,  thus 

1 


2  THE    BENDIGO   GOLD-FIELD. 

presenting  a  contrary  or  westward  dip  to  the  extent  of  the  width  of 
the  belt.  This  width,  measured  upon  the  westward  dip,  varies  for 
the  "runs"  in  this  mine  from  150  to  200  feet.  Along  the  strike 
they  have  been  followed  north  and  south  for  several  hundred  feet, 
but  the  extent  of  their  development  necessarily  depends  upon  eco- 
nomic considerations,  the  amount  of  gold  they  carry  and  the  hard- 
ness of  the  rock  they  traverse.  In  the  Catherine  Reef  United,  the 
two  shafts  are  947  feet  apart,  and  one  run  of  spurs  has  been  traced 
throughout  this  distance  and  300  feet  beyond.  Such  a  network  may 
have  its  regular  course  disturbed  by  faults,  and  is  subject  to  the 
irregularities  of  strike  and  dip  which  usually  characterize  such  for- 
mations. 

In  this  mine  the  bed  richest  in  spurs  and  most  productive  in  gold 
is  the  "forty-foot  sandstone  "  (see  Fig.  1),  so  called  from  its  thick- 
ness. It  is  overlain  by  the  ten-foot  slate,  the  two-foot  sandstone 
and  the  five-foot  slate.  The  two-foot  sandstone  is  so  hard,  and  forms 
so  marked  a  feature  of  the  underground  workings,  that  the  miners 
have  named  it  "  The  Devil's  Back/'  and  by  this  term  it  is  generally 
known.  Underneath  and  west  of  the  forty-foot  sandstone  comes  a 
regular  series,  including,  in  the  order  named,  the  eighteen-foot  slate, 
the  thirty-foot  sandstone,  the  six-foot  slate,  the  eighteen-foot  sand- 
stone and  the  thirty-five- foot  slate.  The  wider  beds  of  sandstone 
are  often  subdivided  by  slate  partings,  as  the  thirty-foot  slate,  for  in- 
stance, is  cut  up  by  several  thin  seams  of  sandstone.  The  divisions 
into  slate  and  sandstone  are  frequently  somewhat  arbitrary,  since 
there  are  rocks  of  intermediate  composition,  sandy  slate  and  slaty 
sandstone,  recognized  by  the  miners  as  "bastard  slate7'  and  "bas- 
tard sandstone."  The  main  divisions  into  the  "bars"  or  beds  of 
stated  thickness  are  determined  at  the  time  of  driving  the  cross-cuts, 
when  the  drill  decides  the  question  of  relative  hardness  and  fracture. 

The  spurs  worked  in  the  forty-foot  sandstone,  in  the  stopes  above 
the  676-foot  level,  will  serve  as  illustrations.  Figs.  2  and  3  are  re- 
produced from  the  sketches  made  underground.  In  Fig.  2,  A  is  the 
bed  of  sandstone  dipping  east  and  penetrated  by  a  series  of  quartz- 
veins  inclining  flatly  to  the  west.  These  do  not  penetrate  the  over- 
lying slate  B,  but  they  are  found  in  the  underlying  bed  C,  where  their 
position  is  almost  invariably  changed  to  a  steeper  angle.  The  frac- 
tures filled  with  quartz  have  many  of  the  features  of  joints,  as  shown 
in  Fig.  3,  which  illustrates  the  same  bed  of  sandstone  in  another 
part  of  the  mine,  where  it  is  barren  of  quartz  but  fractured  in  lines 
which  are  almost  at  right  angles  to  the  plane  of  bedding. 


THE    BENDIGO   GOLD-FIELD.  3 

The  width  of  a  breast  (4  feet)  in  the  stopes  ordinarily  shows  an 
average  of  three  spurs,  the  largest  about  8  inches  and  the  smallest  1 J 
inches  in  thickness,  giving  an  average  width  of  15  inches  of  quartz 
in  the  4  feet  of  sandstone  rock  broken  for  the  mill. 

In  Fig.  4  a  longitudinal  section  is  presented,  as  seen  in  the  north 
stopes  of  the  676-foot  level.  It  will  be  noted  that  the  spurs  pitch 
to  the  north,  their  dip  being  (as  we  have  seen)  to  the  west.  Lines  of 
cross-fracture  or  jointage  are  indicated.  The  upper  spur  A  carries 
an  inclusion  of  country  C.  This  is  considered  favorable  to  the 
occurrence  of  gold,  which,  as  in  ordinary  vein-mining,  often  "  makes 
at  the  point  of  a  horse."  The  lower  spur  B  shows  two  splices. 

Fig  5  illustrates  a  behavior  on  the  part  of  the  spurs,  which  is 
characteristic  of  them  all  over  the  gold-field.  A  quartz-seam,  upon 
leaving  a  bed  of  sandstone  and  entering  one  of  slate,  invariably  turns 
its  dip  in  sympathy  with  the  cleavage  of  the  slate.  Frequently  a 
big  "  blow  "  or  irregular  body  of  quartz  is  formed  in  the  slate  sepa- 
rating two  beds  of  sandstone.  This  is  very  marked  in  the  case  of  the 
ten-foot  slate,  as  shown  in  Fig.  5,  where  S  S  are  spurs,  A  is  the  forty- 
foot  sandstone,  B  the  ten-foot  slate,  C  the  "  Devil's  Back,"  and  D 
the  five-foot  slate. 

The  "  leaders,"  the  position  of  which  is  marked  on  the  general 
cross-section  (Fig.  1),  form  a  marked  feature,  and  are  useful  guides 
in  the  underground  workings.  They  are  essentially  thin  seams  of 
quartz  and  clay,  following  the  line  of  parting  between  certain  mem- 
bers of  the  series  'of  slate  and  sandstone  beds.  The  thickness  of 
quartz  which  they  carry,  though  not  uniform,  is  usually  limited  to  4 
or  5  inches,  and  they  are  accompanied  by  a  variable  amount  of  graph- 
itic clay,  derived  from  the  softer  of  the  two  bounding  walls.  It  will 
be  noted  that  in  every  case  save  one  the  overlying  bed  is  sandstone 
and  the  underlying  slate.  In  these  cases  the  leaders  carry  a  very  clean 
hanging-wall,  often  showing  smooth,  polished  surfaces,  sometimes 
also  marked  by  strice.  The  foot-wall  country  exhibits  a  variable 
amount  of  distortion,  and  is  frequently  in  a  crushed  condition  for  2 
or  3  feet  below  the  black  clay  or  mud  of  the  leader  into  which  it 
gradually  merges. 

Following  the  stratification  as  they  do,  the  leaders  may  be  con- 
sidered true  bed- veins.  There  is  abundant  evidence  that  the  plane 
of  parting  which  they  follow  has  also  been  a  plane  of  movement  of 
the  enclosing  rocks,  and  that  the  black  clay  which  is  one  of  their 
chief  characteristics  is  the  result  of  the  attrition  which  has  crushed 
the  softer  slate  constituting  one — usually  the  lower — of  the  two  sur- 
faces in  contact. 


4  THE   BBNDIGO   GOLD-FIELD. 

In  the  development  of  the  mine,  such  a  leader  is  often  found  to  be 
the  apparent  starting-line  of  a  series  of  spurs.  It  is  also  found  that 
the  latter  are  frequently  faulted  by  the  former.  The  second  fact  ex- 
plains the  first.  Occasionally,  the  displacement  is  so  small  as  to  be 
of  no  importance  to  the  miner,  though  interesting  to  the  geologist. 

Fig.  6  illustrates  "the  leader/' so-called  to  distinguish  it  from 
the  "  east,"  "  west,"  and  "black"  leaders,  shown  in  Fig.  1.  The 
sketch  was  made  in  a  short  cross-cut  from  the  676-foot  level.  The 
leader  D  separates  the  forty-foot  sandstone  A  from  the  eighteen- 
foot  slate  B.  It  consists  of  a  thin  but  regular  vein  of  quartz  E, 
accompanied  with  black  clay  or  fluccan,  varying  from  one  to  three 
inches  in  thickness.  The  spur  S  in  the  forty-foot  sandstone  is  seen 
to  reappear  in  the  eighteen-foot  slate  ;  but  in  crossing  the  line  of  the 
leader  it  has  been  dislocated  and  broken.  The  throw  is  two  feet. 
C  C  are  fragments  of  quartz  broken  off  the  spur  by  the  movement 
along  the  plane  of  the  leader.  The  greater  resistance  offered  at  this 
particular  point  by  the  quartz  of  the  spur  has  caused  a  local  increase 
of  the  thickness  of  crushed  material ;  and  consequently  there  is  a 
width  of  4  or  5  inches  of  black  clay  between  the  two  faulted  por- 
tions of  .the  spur. 

Fig.  7  shows  the"  black  leader,"  so-called  because  in  this  instance 
quartz  is  frequently  absent,  and  entirely  replaced  by  graphitic  clay. 
The  unusual  thickness  of  the  latter  is  explained  by  the  fact  that  the 
overlying  bed  A,  the  eighteen-foot  sandstone,  has  more  than  ordinary 
hardness,  while  B,  the  underlying  thirty-five  foot  slate  is  compara- 
tively soft.  The  sandstone  forms  a  straight,  clean,  polished  hanging- 
wall.  The  leader  0  carries  imbedded  in  the  clay  small  pieces  of 
quartz,  probably  the  shattered  remnants  of  quartz-veins  broken 
through  by  the  movements  along  the  plane  of  the  leader.  The  width 
is  about  4  inches.  The  underlying  slate  is  much  crushed  and  dis- 
turbed near  the  leader  and  is  full  of  distorted  threads  and  irregular 
pieces  of  quartz,  which  become  regular  spurs  at  no  great  distance 
from  the  leader. 

In  Fig.  8  the  "  east  leader  "  is  illustrated.  The  sketch  was  made 
in  the  stopes,  called  the  "No.  13  backs,"  above  the  870-foot  level, 
main  shaft.  This  leader  follows  the  line  of  parting  b'etween  the 
thirty-foot  sandstone  and  the  six-foot  slate.  A  and  B  indicate  the 
thirty-foot  sandstone,  of  which  the  part  B  is  beginning  to  be  marked 
by  slaty  cleavage.  C  and  D  are  the  six-foot  slate  which,  near  the 
leader,  is  sandy.  The  country  on  the  two  sides  of  the  parting  has  a 
nearly  equal  hardness,  which  explains  the  fact  that  this  leader  is  no- 


THE   BENDIGO   GOLD-FIELD. 


6  THE   BENDIGO   GOLD-FIELD. 

tably  narrow  and  is  accompanied  by  an  unusually  small  amount  of 
graphitic  clay.  The  sketch  shows  a  fault  to  have  taken  place.  The 
throw  is  about  12  inches.  Between  the  upper  and  lower  portions  of  the 
spur  S  the  leader  L  is  accompanied  by  a  small  quartz  seam  T.  Though 
this  is  very  small,  the  fact  that  the  two  larger  portions  of  the  spur 
are  connected  points  to  the  conclusion  that  the  faulting  of  the  frac- 
ture in  which  the  quartz  of  the  spur  was  deposited  took  place  before 
the  deposition  of  that  quartz,  which,  following  the  upper  portion  of 
S,  was  arrested  by  the  leader  or  parting  between  the  two  beds  B  and 
C ;  that  it  followed  the  line  of  fault,  namely  the  leader,  as  the  seam 
T,  and  then  resumed  its  course  along  the  lower  portion  of  the  faulted 
fracture.  The  reason  for  the  narrowing  of  the  quartz  deposited 
along  T  was,  that  the  fracture  between  the  two  beds  was  very  nar- 
row and  straight,  not  affording  such  facilities  for  deposition  as  were 
given  by  the  more  irregular,  broken  and  more  horizontal  fractures 
across  and  in  the  country-rock  itself. 

While  minor  faults  are  found  along  the  leaders,  the  latter  are 
themselves  dislocated  by  larger  faults,  coming  in  from  the  west. 
Fig.  9  shows  one  of  these,  as  seen  in  the  north  stopes  of  the  1140- 
foot  level.  F  is  the  line  or  wall  of  the  fault.  The  throw  is  from  A 
to  B,  12  feet.  The  structural  effects  of  the  fault  upon  the  country 
(and  therefore  upon  those  fractures  in  the  country  which  after  the 
faulting  became  the  depositories  of  quartz)  are  shown  by  the  spurs 
S  S,  which,  though  not  broken,  have  here  departed  from  their  usual 
west  dip,  and  incline  slightly  east.  At  a  short  distance  from  the 
fault  they  are  seen  to  resume  their  normal  position.  The  seam  lining 
the  fault-fissure  is  formed  of  quartz  of  a  different  character  from 
that  of  the  spurs  themselves.  Fig.  10  illustrates  another  similar 
fault,  this  time  in  the  stopes  above  the  1070-foot  level,  north  of  the 
shaft.  The  throw  is  15  feet.  The  spurs  are,  as  in  the  previous  case, 
distorted  in  sympathy  with  the  fault,  the  line  of  which,  F  F,  is 
accompanied  by  three  or  four  inches  of  crushed  material. 

Lava  dikes  are  not  often  seen  in  this  mine ;  but  Fig.  11  illustrates 
their  characteristic  features,  due  to  their  later  origin,  in  this  gold- 
field.  Here  the  lava  dike  T,  seeking  the  lines  of  least  resistance, 
traverses  a  bed  of  sandstone  until  it  meets  with  a  fault,  which  it  fol- 
lows for  a  short  distance  before  taking  to  a  bedding  plane,  which  it 
in  turn  leaves  to  accompany  a  joint  fracture  before  finally  resuming 
its  course  along  the  line  of  parting  between  two  beds. 

The  modes  of  occurrence  of  the  gold,  as  observed  in  this  mine, 
present  many  points  of  interest.  Figs.  12  and  13  are  longitudinal 


THE   BENDIGO   GOLD-FIELD. 


UJ         Q 

UJ      UJ 


OJ       _| 

z:    < 


£     I- 


8  THE    BENDIGO   GOLD-FIELD. 

and  cross-sections  of  two  spurs,  A  and  C,  as  seen  in  the  1118-foot 
stopes.  At  and  near  the  point  marked  with  a  cross  in  Fig.  12  there 
was  found,  on  the  day  of  ray  first  visit  underground,  a  very  rich 
bunch  of  gold-quartz.  The  spur  C,  though  particularly  gold- 
bearing  at  its  intersection  with  the  diagonal  spur  B,  was,  however, 
also  rich  for  many  feet  in  length.  The  quartz  was  white,  some- 
what crushed  and  friable.  The  gold  was  coarse  and  could  readily 
be  separated  from  the  enclosing  quartz  by  the  point  of  a  drill.* 
This  spot  afforded  a  typical  example  of  the  generally  coarse  char- 
acter and  iregular  distribution  of  the  gold  in  spurs. 

Fig.  13,  a  cross-section  of  the  spurs  A  and  B  shown  in  Fig.  12, 
illustrates  the  almost  invariable  rule  that  the  quartz- veins  traversing 
the  rocks  of  this  district  cut  across  the  sandstone,  and  travel  along 
the  cleavage  lines  of  the  slate.  Fig.  14  shows  other  spurs  traversing 
the  beds  C,  D  and  E,  which  follow  the  same  rule. 

The  appearance  of  the  quartz  forming  the  ore  of  the  Catherine 
Reef  United  mine  would  be  considered  in  most  other  districts  unfa- 
vorable to  the  presence  of  gold.f  It  is  very  white  and  often  some- 
what sugary.  Again,  a  miner  usually  dislikes  vugs  or  geodes  in  a 
gold-quartz  vein  ;  but  here  they  are  often  accompanied  by  gold,  fre- 
quently pseudomorphic  after  mundic.  "Black  Jack  "  or  zinc-blende, 
arsenical  iron  pyrites  and  mundic,  are  the  minerals  accompanying 
the  gold.  Of  these  the  last  is  present  in  the  largest  proportion.  It 
is  coarsely  crystalline  and  appears  to  favor  the  smaller  spurs,  par- 
ticularly in  the  parts  nearest  the  enclosing  sandstone.  Galena  is  not 
often  seen,  but  is  considered  favorable  to  the  presence  of  gold.  The 
gold  is  generally  coarsej  and  of  high  caratage.  It  is  often  visible, 
and  invariably  so  in  rich  ores.  Pieces  weighing  7  dwt.,  4  dwt.,  and 
many  of  two  and  three  dwt.  have  been  taken  out  of  one  spur,  at 
depths  exceeding  1000  feet  from  the  surface.  As  a  rule  the  gold  is 
less  coarse  and  more  evenly  disseminated  in  spurs  which  traverse  the 
slate  than  in  those  found  in  the  sandstone.  It  would  be  hazardous 


*  It  is  the  custom  of  the  mine  manager,  in  making  his  daily  rounds  of  the  work- 
ings, to  remove  and  take  with  him  the  more  tempting  pieces  of  gold  exposed  in  the 
spurs;  and  at  this  place  we  spent  an  interesting  half-hour  in  breaking  away  the 
richest  of  the  "  stone,"  which  showed  gold  in  particles  as  large  as  peas. 

f  Miners  elsewhere  would  characterize  it  as  "  wild,"  "  rash,"  "bastard,"  or  "  bull 
quartz." 

£  As  indicated  by  the  retorts  in  the  mill.  For  instance  a  test  lot  of  ore  (46  tons) 
gave  42  ounces  of  amalgam  from  which,  on  retorting,  34  oz.,  15  dwt.  of  gold  were 
obtained. 


THE   BENDIGO   GOLD-FIELD. 


10  THE   BENDIGO  GOLD-FIELD. 

to  say  that  the  slate  is  more  auriferous  than  the  sandstone,  though 
the  experience  of  the   manager*  points  that  way. 

Notwithstanding  the  occurrence  of  rich  specimens,  and  the  gene- 
ral coarseness  and  purity  of  the  gold,  this  mine  presents,  from  a 
business  standpoint,  what  is  familiarly  known  as  a  "  low-grade 
proposition/'  The  character  of  the  work  done  is  indicated  by  the 
following  figures.  During  six  months  (1891)  11,080  tons  were 
mined  and  crushed,  yielding  2583  oz.,  12  dwt.  of  gold,  an  average 
per  ton  of  4  dwt.,  16  gr.  (including  34  tons  of  pyrites  yielding  66 
oz.,  5  dwt.).  One  dividend  of  sixpence  per  share  on  67,600  shares, 
was  paid  during  that  period. 

THE  NEW  RED,  WHITE  AND  BLUE  CONSOLIDATED. 

This  mine,f  situated  at  the  other  end  of  the  Bendigo  district, 
affords  another  interesting  example  of  a  spur  formation.  Though  a 
much  smaller  mine  than  the  Catherine  Reef  United,  it  is  at  present 
one  of  the  best  producers^  upon  the  gold-field. 

Work  is  confined§  to  three  levels,  660,  760  and  820  feet  respec- 
tively from  the  surface.  The  main  stopes,  where  the  best  sections  of 
the  ore-deposit  are  obtainable,  are  above  the  760-foot  level.  That 
portion  of  the  country  in  which  the  spurs  are  found  dips  to  the  east. 
The  formation  or  "  make  of  spurs  "  pitches  south,  the  individual 
spurs  having  a  variable  direction.  So  far,  the  opening  up  of  the  mine 
has  not  led  to  the  recognition  of  "  leaders,"  such  as  those  noted  in  the 
Catherine  Reef  United ;  but  the  country  is  traversed  by  "walls" 
having  smooth  faces  and  accompanied  by  black  clay,  which  also  dip 
eastward,  cutting  the  bedding  at  a  small  angle.  The  wedges  of  rock 
thus  formed  between  the  "  walls  "  and  the  planes  of  bedding  neces- 
sitate extra  care  in  timbering  the  mine.  These  "walls"  have  been 
lines  of  movement;  and  frequently  the  extent  of  the  faulting  can 
be  determined.  Like  the  "  leaders  "  elsewhere,  they  are  found  to 
separate  barren  from  auriferous  ground,  and  hence  are  accepted  as 

*  Mr.  Robert  Coates,  to  whom  I  am  indebted  for  courtesy  and  for  valuable  infor- 
mation. 

f  The  original  claim  received  its  name  from  its  first  operators,  a  company  of  sailors 
who  had  deserted  their  ships  in  Port  Philip  Bay,  and  taken  to  mining.  On  gala 
days  they  were  in  the  habit  of  decorating  the  works  with  red,  white  and  blue  flags. 

J  For  the  quarter  ending  September  30,  1891,  this  mine  produced  5174  tons, 
yielding  2815  oz.,  15  dwt.,  and  averaging  10  dwt.,  21  gr.  per  ton.  During  the  same 
period  the  fortnightly  dividends  amounted  to  £5625. 

$  My  notes  are  from  visits  made  in  September  and  October,  1890.  I  would  ex- 
press my  thanks  to  Mr.  Wm.  Hicks,  the  manager,  for  his  courtesy. 


THE   BENDIGO   GOLD-FIELD. 


11 


12  THE   BENDIGO   GOLD-FIELD. 

guides  in  the  development  of  the  auriferous  portion  of  the  "  make  of 
spurs." 

Lava  dikes  are  often  seen  in  the  workings  of  this  mine.  One  in 
particular  can  be  followed  through  the  different  levels  and  stopes, 
and  is  of  economic  importance  in  that  it  is  held  to  limit  the  "  run  of 
spurs"  in  the  ground  above  the  760-foot  level,  although,  below  that 
level,  it  crosses  the  ore-channel.  The  penetration  of  the  country-rock 
by  the  dikes  is  the  most  recent  occurrence  in  its  structural  history  ; 
and  the  supposition  of  their  agency  in  enriching  certain  portions  of 
an  ore-shoot  or  spur-formation  is  an  error,  based  upon  accidental  co- 
incidences; In  the  above  case,  for  instance,  the  lava  follows,  for  a 
certain  distance,  one  of  the  "  walls,"  which  it  then  leaves  to  take  an 
independent  line  across  the  country.  While  following  the  wall  it 
limits  the  gold-bearing  ground.  Previous  faulting  along  the  plane 
of  the  wall  may  have  brought  highly  auriferous  rock  opposite  to  that 
which  is  barren :  and  where  this  result  is  observed  in  contact  with 
the  later  lava-dike,  it  is  natural,  but  erroneous,  to  ascribe  to  the  in- 
fluence of  the  dike  what  is  in  fact  the  effect  of  an  earlier  displace- 
ment and  separation  of  two  portions  of  an  ore-shoot,  along  a  plane 
of  movement  with  which  the  dike  happens  to  coincide  in  its  local 
position. 

The  accompanying  sketches  will  illustrate  the  different  structures 
seen  underground  in  this  mine.  Fig.  15,  is  a  sketch  taken  in  the 
stopes  above  the  760-foot  level.  The  bedding  is  indicated  by  the 
arrow.  H  H  is  called  the  hanging- wall  of  this  part  of  the  stoping- 
ground,  that  is,  it  is  accepted  as  the  upper  or  eastern  limit  of  the 
auriferous  formation.  The  rock  on  the  upper  side  is  hard  sandstone. 
The  "  wall  "  is  smooth,  shows  a  graphitic  lining  and  carries  a  little 
clay.  It  is  a  fault,  but  the  amount  of  throw  I  could  not  determine 
owing  to  the  disordered  structure  of  the  country.  A  is  sandstone, 
threaded  by  quartz-veins.  B  is  slaty  sandstone,  disordered  and  car- 
ying  veins  of  quartz  C,  parallel  to  the  ba.ltlin^.  D  is  soft,  black, 
broken-op  rock,  likewise  carrying  quartz  E;  the  sandstone  F  also 
showing  twisted  pieces  of  quartz,  of  short  length.  G  is  slate.  T  is 
the  lava  dike,  here  two  feet  wide,  black  and  homogeneous.  It  hugs 
a  "wall,"  nearly  parallel  to  that  which  bounds  the  other  side  of  the 
formation. 

Turning  round  and  looking  south,  one  sees  the  other  end  of  the 
stopes,  as  shown  in  Fig.  16.  This  is  40  feet  from  the  point  illus- 
trated in  Fig.  lo.  The  beds  A,  B,  F,  G  consist  of  sandstone,  slaty 
sandstone,  sandstone  and  slate  respectively,  corresponding  to  the 


THE   BENDIGO   GOLD-FIELD. 


13 


14  THE  BENDIGO   GOLD-FIELD. 

opposite  breast  of  the  works.  C  is  massive  quartz,  more  white  and 
less  auriferous  than  the  narrow  spurs  E  E,  with  their  interlacing 
quartz-veins.  T  is  the  dike. 

Fig.  17  representing  another  part  of  the  stopes  above  the  760-foot 
level,  shows  how,  in  this  mine,  the  quartz  of  the  spurs  follows  some- 
times the  planes  of  bedding,  sometimes  cross-fractures.  Close  exami- 
nation of  the  ground  is  usually  required  to  distinguish  the  bedding. 
The  broken  line  on  the  parting  between  beds  C  and  D  in  this  figure 
denotes  that  this  boundary  is  very  indistinct.  This  instance  ex- 
hibits again  the  behavior  of  the  spurs,  already  repeatedly  mentioned, 
in  u  following  "  the  slate,  while  cutting  across  the  sandstone.  (See, 
for  example,  spur  a,  6,  c.) 

Fig.  18  shows  the  structure  of  the  breast  of  the  760-foot  level.  D 
is  slate  which,  near  A,  is  black  and  broken.  A  is  a  quartz-vein 
separated  into  two  portions  by  the  strip  of  black  slate  E,  which  last 
carries  a  notable  amount  of  pyrites.  B  is  hard  sandstone.  G  and 
H  are  both  slate,  well  marked  by  cleavage  and  appearing  to  be  di- 
vided portions  of  the  same  bed.  C  is  a  channel  of  soft  country, 
streaked  with  quartz  and  underlying  the  dike  T;  while  F  is  a 
vein  of  quartz,  and  O  is  sandstone.  It  will  be  noted  that  the  coun- 
try has  been  dislocated  and  that  the  lava  follows  the  line  of  the  fault- 
fracture,  which  is  also  indicated  by  the  soft  broken  country  marked 
C.  Fig.  19  shows  on  a  larger  scale  the  cross-hatching  of  quartz 
which  occurs  at  the  point  marked  K  in  Fig.  18. 

Previous  to  the  discovery  of  the  gold-bearing  character  of  this 
spur-formation,  the  work  of  the  mine  was  confined  to  what  is  known 
as  the  "  Sheepshead  main  reef,"  a  large  lode  of  massive  quartz  which 
is  cut  by  the  760-foot  workings.  As  there  exposed,  it  is  from  12  to 
14  feet  wide,  conformable  with  the  bedding,  and  separated  from  the 
spur-formation  now  worked  by  30  feet  of  very  hard  sandstone.  This 
lode  of  quartz  does  not  extend  upward  so  far  as  the  660-foot,  nor 
down  so  far  as  the  820-foot  level,  but  was  worked  along  the  strike 
for  70  feet  north  and  169  feet  south  of  the  shaft.  It  is  uniformly 
poor. 

The  "  run  of  spurs  "  is  worked  in  this  mine  for  a  width  of  20  to 
25  feet.  Its  extent  north  and  south  is  not  yet  known.  The  forma- 
tion is  subject  to  irregularities  of  several  kinds ;  but  occasionally  it 
has  a  well-defined  character,  that  of  a  series  of  quartz  seams  confined 
to  a  certain  narrow  belt  of  country.  The  number  and  size  of  the 
spurs  is  always  varying.  Sometimes  one  or  two  rich  spurs  pay  for 
the  removal  of  a  large  width  of  poor  rock ;  sometimes  the  sandstone 


THE    BEXDIGO   GOLD-FIELD. 


15 


WH^r*.. 


OJ 

L 


16  THE   BENDIGO   GOLD-FIELD. 

is  so  penetrated  by  a  ramification  of  veins  as  to  be  substantially  a 
quartz-lode.  Gold  is  often  visible,  especially  in  one  or  two  particu- 
lar spurs,  comparatively  narrow  (say,  2  to  3  inches),  which  maintain 
their  individuality  for  a  considerable  distance — 10  to  25  yards.  The 
ground  is  easily  broken,  but  requires  careful  filling  and  timbering. 
The  ore  as  sent  to  the  surface  looks  as  if  it  comprised  75  per  cent  of 
barren  slate  and  sandstone.  It  will  be  understood  that  careful  sort- 
ing is  out  of  the  question,  on  account  of  the  low  grade  of  the  quartz. 
A  representative  fortnightly  yield  is  559  oz.,  14  dwt.  of  gold  from 
641  tons.* 

THE  HERCULES  AND  ENERGETIC. 

In  my  first  paper  on  the  Bendigo  district,  reference  was  made  to 
a  quartz* formation  known  locally  under  the  generic  terra  of  "lode." 
Such  is  that  which  has  been  developed  in  the  Hercules  and  Ener- 
getic mines  at  Long  Gully.  The  "lode"  is  called  the  Victoria, 
from  the  mine  where  it  had  its  greatest  development;  but  it  is 
really  a  portion  of  the  main  New  Chum  formation.  It  consists  of 
a  channel  of  more  or  less  shattered  country-rock,  threaded  by  quartz- 
veins,  some  of  which  traverse  it  irregularly,  while  others  are  parallel 
to  the  bounding  walls.  In  dip  and  strike  it  is  conformable  with 
the  enclosing  country.  It  may  therefore  be  pronounced,  in  the  first 
place,  a  " bed-vein/'  as  distinguished  from  a  "true  fissure;"  but  it 
may  be  also  looked  upon  as  a  degenerated  "  leg"  of  a  saddle-formation, 
or  again,  as  an  exaggerated  "  leader."  Since  it  evidently  occupies  a 
line  of  movement,  it  can  be  called  a  fault  or  "slide,"  the  filling  of 
which  is  occasionally  auriferous.  In  this  mine  it  is  sometimes  called 
"  the  Victoria  back,"  which  means  simply  that  the  wall  continues 
when  the  accompanying  quartzose  and  other  material  has  "  pinched 
out."  In  any  case,  it  illustrates  very  forcibly  the  difficulty  of  apply- 
ing arbitrary  definitions,  and  the  absurdity  of  careless,  dogmatic 
labelling. 

The  "  back,"  that  is,  the  upper  and  best  defined  wall  of  the  lode, 
serves  as  the  main  guide  in  the  development  of  the  mine.  Besides 
the  lode  which  "  makes  up  against  it,"  there  are  in  its  neighborhood 
channels  of  country  which  carry  spurs.f  Sometimes  both  lode  and 

*  Since  the  time  of  niy  visit,  the  mine  has  continued  to  give  excellent  returns, 
and  is  to-day  the  premier  dividend-paying  property  in  this  gold-field.  It  was  an 
abandoned  mine  at  one  time,  and  owes  its  present  position  to  the  enterprise  of  Mr. 
Geo.  Lansell. 

t  I  am  reminded  in  this  connection  of  a  remark  made  by  Mr.  Northcote,  the 
manager  of  the  180  mine,  to  the  effect  that  "backs  "  often  formed  the  boundaries  to 
the  gold-bearing  portion  of  an  ore-channel. 


THE   BENDIGO   GOLD-FIELD. 


17 


spurs  are  sufficiently  gold-bearing  to  warrant  exploitation,  sometimes 
the  lode  but  not  the  spurs,  or  vice  versa. 

Nearly  parallel  to  the  "  main  back,"  there  are  other  divisions  in 
the  country,  which  are  called  "  leaders."  These  are  simply  lines  of 
movement  in  sympathy  with  a  main  fault,  and  are  marked  by  small 
clay  seams.  They  tend  to  meet  the  main  lode  on  its  dip  ;  and  at  the 
junctions  so  formed,  large  bodies  of  ore  have  been  found  and  profit- 


-  20. 


\XT 


HERCULES  AND  ENERGETIC 


ably  worked.  Bodies  of  quartz  as  much  as  40  feet  wide  have  been 
discovered  under  these  conditions,  bounded  to  the  west  by  the 
"  back,"  but  breaking  into  spurs  towards  the  east.  These  spurs  cut 
through  the  so-called  "  leaders"  and  are  found  richest  at  the  inter- 
section. An  example  may  be  seen  in  Fig.  20,  where  A  A  indicates 
the  main  back,  and  B  is  a  large  body  of  quartz  breaking  eastward 
into  the  spurs  S  S,  while  C  C  are  the  "  leaders."  The  spurs  are 
more  flat,  and  there  are  more  good  spurs  in  the  sandstone  than  in 

2 


18  THE    BENDIGO    GOLD-FIELD. 

the  slate;  although  if  a  good  (i.e.,  a  highly  gold-bearing)  spur 
traverses  more  than  one  bed  of  the  country,  it  is  not  found  notably 
poorer  in  the  slate.  The  gold  is  coarsest  in  the  sandstone.  It  is 
also  noted  that  frequently  the  heaviest  gold  is  on  the  foot-wall  or 
lower  part  of  any  given  spur. 

At  the  600-foot  level,  the  "Victoria  lode"  consists  of  a  bed  of 
black  slaty  material,  containing  threads  of  quartz  which  carry  both 
coarse  and  fine  gold.  The  manager  informed  me  that  the  gold  in  the 
slate  was  more  flaky  than  that  found  in  the  quartz  of  the  sandstone 
which  was,  on  the  contrary,  granular.  In  this  part  of  the  mine  the 
lode  dips  about  70°  to  the  east,  and  strikes  20°  west  of  north,  which 
is  the  strike  of  the  New  Chum  Reef. 

At  the  1020-foot  level,  the  lode  has  a  remarkably  clean,  straight 
hanging-wall.  A  sketch  made  in  this  level,  facing  south,  is  shown 
in  Fig.  21.  A  is  the  main  wall;  B  is  black,  crushed  slaty  filling, 
containing  a  large  proportion  of  quartzose  matter ;  C  is  sandstone, 
here  notably  nodular ;  D  is  a  thin  slaty  parting  between  the  sand- 
stone C  and  the  bed  of  slate  E,  which  contains  a  network,  9  feet 
wide,  of  quartz-veins.  The  cleavage  is  indicated. 

Forty  feet  below  this  level,  or  at  1060  feet  below  the  surface,  the 
lode  is  faulted;  and  close  to  the  point  of  dislocation  there  was  found 
a  body  of  remarkably  rich  quartz,  of  which  46  tons  gave  an  average 
yield  of  46 \  oz.  per  ton,  producing  over  2000  oz.  of  gold.  The  Vic- 
torian Mining  Department  deputed  Mr.  E.  J.  Dunn,  F.  G.  S.,*  to 
examine  this  occurrence;  and  his  description  appeared  in  the  Quar- 
terly Mining  Report  of  March,  1890.  My  sketch,  Fig.  22,  differs 
but  little  from  his,  except  in  minor  details.  S  S  marks  the  line  of 
the  fault ;  A  is  the  lode.  It  will  be  noted  that  the  throw  of  the 
fault  is  equal  to  the  width  of  the  lode.  The  line  of  the  fault  is 
marked  by  a  wall,  accompanied  with  black  graphitic  clay  of  vary- 
ing width,  while  the  country  included  within  the  limits  of  the  lode 
is  shattered  and  traversed  by  a  number  of  quartz- veins,  of  varying 
size  and  direction.  There  is  every  gradation  from  clean  black  slate 
to  clean  white  quartz.  The  broken  portions  of  included  country 
have  become  so  interpenetrated  by  minute  quartz- veins  that  it  is  im- 
possible to  say  where  the  quartz  begins  and  where  the  slate  ends. 
Locally  it  would  be  termed  an  extreme  case  of  a  "  mullocky  "  reef. 
The  cleavage  cuts  through  the  slaty  filling  of  the  lode. 

*  This  gentleman,  one  of  the  leading  colonial  geologists,  has  recently  been  en- 
gaged in  the  preparation  for  the  Victorian  Mining  Department,  of  a  monograph 
upon  the  Bendigo  gold-field,  which  is  to  be  published  shortly. 


THE   BENDIGO   GOLD-FIELD. 


19 


20  THE   BENDIGO   GOLD-FIELD. 

At  the  point  marked  with  a  cross,  in  a  space  8  feet  square,  there 
was  obtained  £9000  worth  of  gold.  When  I  saw  it,  the  ore  ex- 
hibited a  notable  absence  of  the  considerable  percentage  of  pyrites, 
usually  present  in  the  richer  ore- bodies  of  the  district;  but  I  was  in- 
formed that  at  the  time  of  working  the  "  rich  patch  "  there  was 
"  plenty  of  mundic."*  The  gold  was  comparatively  fine,  the  amal- 
gam at  the  mill  yielding  one-third  when  retorted.  The  material  a 
few  feet  away  from  this  particular  rich  spot  was  valueless,  although, 
as  the  manager  said,  somewhat  similar  in  appearance  to  that  which 
had  been  so  valuable. 

The  fault  here  observed  has  been  encountered  also  at  the  1120,- 
1220-  and  1320-foot  levels,  keeping  a  uniform  direction,  though  the 
width  of  broken  country  is  subject  to  much  variation,  owing  to  the 
varying  hardness  and  structure  of  the  beds  traversed.  Fig.  23  is  a 
sketch  of  the  fault  or  "  slide,"  as  seen  in  the  west  drift  of  the  1220- 
foot  level.  It  has  there  a  width  of  4  feet,  and  consists  of  broken 
country,  mixed  with  quartz.  The  quartz  A  upon  the  under  wall  is 
10  inches  wide,  but  njn-auriferous.  Stringers  and  irregular  lumps 
of  quartz  are  scattered  through  the  soft  black  crushed  slate  B.  There 
is  a  "  dig  "  or  mud-seam  C  upon  the  hanging-wall,  only  differing 
from  the  broken  slate  in  being  more  finely  comminuted.  The  cleav 
age  is  shown  in  the  figure. 

The  sketches  given  indicate  the  great  similarity  between  the  struc- 
ture of  the  fault  and  that  of  the  lode.  In  fact,  they  both  mark 
lines  of  improvement ;  but  the  latter  follows  the  bedding,  while  the 
former  crosses  it ;  one  is  a  cross-fissure  while  the  other  is  a  bed-vein. 
Economically,  they  present  the  important  difference  that  one  is  un- 
doubtedly more  auriferous  than  the  other. 

The  discovery  above  mentioned,  of  the  rich  ore-body  at  the  1060- 
foot  level  (which  was  almost  accidental,  having  been  made  in  con- 
necting a  winze  with  a  "  rise,"  in  the  course  of  ordinary  working, 
rather  than  of  purposed  exploration),  shows  how  necessary  it  is  to 
prospect  the  mines  thoroughly,  and,  wherever  conditions  known  by 
experience  to  be  favorable  are  present,  to  cut  up  the  ground  carefully 
and  systematically. 

THE  CONFIDENCE  EX-^ENDED. 
This  mine  is  full  of  geological  puzzles,  most  of  which  are  too 

*  These  expressions  are  of  course  relative.  At  Bendigo,  2  per  cent,  of  pyrites 
is  deemed  a  large  amount.  The  concentrates  obtained  in  the  mills  average  1  per 
cent,  of  the  ore. 


THE    BENDIGO   GOLD-FIELD. 


21 


22  THE   BENDIGO   GOLD-FIELD. 

complicated  to  be  unravelled  without  detailed  surveys.*  In  Figs. 
24  and  25,  I  have  given  two  sketches  made  underground  at  the  980- 
foot  level.  In  Fig.  24,  A  is  sandstone  ;  B  is  slate,  having  a  well- 
defined  cleavage;  D  is  quartz;  C  is  sandstone.  At  first  sight,  this 
would  be  put  down  as  an  "  inverted  saddle,"  a  syncline  of  quartz ; 
but,  on  further  study,  the  structure  proves  to  be  as  shown  in  the 
section,  Fig.  25,  where  H,  B,  and  K  are  beds  of  slate,  characterized  by 
marked  cleavage ;  C,  A,  and  L  are  sandstone,  and  the  irregular  de- 
posit on  the  left  of  E  E  is  quartz.  There  is  no  inverted  saddle.  On 
the  other  hand,  this  spot  illustrates  an  interesting  feature  of  the  sand- 
stone beds  of  the  district.  I  refer  to  the  nodular  structure  men- 
tioned already  in  one  previous  instance,  which  is  often  attended  with 
the  deposition  of  quartz.  It  appears  to  me  that  A  is  a  nodule,  due 
to  the  segregation  of  purer  grains  of  sand  from  the  general  body  of 
the  sandstone  bed  C.  Movements  of  the  country  have  caused  frac- 
turing around  the  wedge  formed  between  the  nodule  A  and  the 
bed  of  slate  B;  and  in  the  fractures  so  formed  the  quartz  has  been 
deposited. 

The  east  wall,  E  E,  is  clean  and  straight.  It  can  be  followed, 
unbroken,  throughout  the  workings  of  the  mine.  The  sandstone  A 
is  very  hard  and  fine-grained,  carrying  only  a  few  fine  threads  of 
quartz.  The  sandstone  C  is  coarser  grained  and  not  so  hard,  and  is 
traversed,  near  the  quartz  bodies  which  it  contains,  by  well-marked 
lines  of  cleavage,  which,  while  locally  distorted,  resume  their  nor- 
mal direction  a  little  lower  down.  The  quartz  is  very  heavily  min- 
eralized with  mundic,  and  carries  coarse  gold.  The  formation  pitches 
north.  6f  feet  in  33  feet. 

Fig.  26  was  also  sketched  in  this  mine.  It  represents  an  elemen- 
tary saddle  formation,  as  seen  in  the  1250-foot  level.  B  and  D  are 
beds  of  sandstone,  of  somewhat  similar  composition,  while  A  is  finer 
grained.  The  cleavage  is  indicated.  In  A  there  are  structure -lines, 
along  which  quartz  seams  have  been  formed.  These  lines,  a,  a,  are 
suggestive  of  bedding;  they  are,  in  fact,  what  may  be  termed  "se- 
cret-bedding," lines  of  lamination  marking  the  original  deposition 
of  the  material  forming  the  beds,  and  in  harmony  with  the  main 
lines  of  parting  or  stratification. 

Another  rudimentary  formation  is  seen  in  Fig.  32,  from  the  500- 
foot  level  of  the  same  mine.  In  this  case  we  have  the  beginnings  of 


*  My  thanks  are  due  for  courtesy  shown  to  rae  by  Mr.  Abrahams,  and  afterwards 
by  Mr.  Hall,  managers  of  the  mine. 


THE   BENDIGO   GOLD-FIELD. 


23 


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24  THE   BENDIGO   GOLD-FIELD. 

an  "  inverted  saddle,"  or  syncline  of  quartz.  The  sandstone  A  is 
very  hard,  and  is  threaded  with  quartz.  Along  the  curve  of  the 
parting,  between  the  two  beds,  there  is  a  soft  layer  of  black  clay  or 
"  dig."  D  D,  is  slate,  C  is  quartz. 

Fig.  29  is  a  somewhat  similar  exhibit,  taken  from  the  Whip  and 
Jersey  mine,  at  the  700-foot  level.  Here,  also,  we  have  the  sugges- 
tion of  an  in  verted -saddle  formation.  A  is  hard  sandstone.  C  is 
sandy  slate.  The  dip  is  shown.  There  is  crushed  quartz  and  broken 
country-rock  underneath  the  saddle. 

MISCELLANEOUS  NOTES. 

Several  of  the  mines  which  were  visited  and  examined  by  the 
writer,*  did  not  present  peculiar  features,  though  an  occasional  note 
of  value  was  afforded.  Thus,  at  the  Fortuna  Hustlers,  one  of  the 
youngest  of  the  Bendigo  mines,  and  situated  in  the  heart  of  the  city, 
was  obtained  the  observation  represented  in  Fig.  28.  The  sketch 
represents  the  west  leg  of  the  saddle,  which  is  part  of  the  main 
Hustler's  formation.  C  is  slaty  sandstone,  which  forms  the  clean 
hanging- wall  of  the  reef;  B  is  slate,  A  is  quartz,  D  is  the  very  hard 
sandstone  of  the  foot-wall.  The  cross-cut  clearly  shows  the  forma- 
tion (see  Fig.  27).  The  saddle  pitches  south  ;  the  two  legs,  A  and 
C,  are  only  18  feet  apart;  and  the  bedding  on  the  two  sides  is  seen 
to  correspond.  The  cleavage  is  easterly  above  the  west,  and  westerly 
above  the  east  leg.  Center-country  is  hard  sandstone.  It  is  a  sam- 
ple type  of  the  Bendigo  saddle.  The  shaft  was  sunk,  and  the  gold- 
bearing  reef  was  discovered,  on  inferences  drawn  from  the  informa- 
tion given  by  a  railway  cutting. 

Figs.  30  and  31  illustrate  the  behavior  of  quartz-veins  which  cut 
across  country.  Fig.  30  is  from  the  shaft  of  the  Confidence  Ex- 
tended. A  is  sandstone,  B  is  slate.  The  fracture,  in  which  the 
quartz  was  afterwards  deposited,  could  take  place  as  easily  across  the 
even-grained  and  structureless  sandstone  as  in  any  other  direction, 
but,  when  it  entered  the  slate,  the  line  of  least  resistance  was  found 
to  be  with,  rather  than  across,  the  cleavage.  In  Fig.  31,  from  the 
Garden  Gully  United,  the  same  behavior  is  shown,  though  in  a 
somewhat  different  way. 

Figs.  33,  34,  and  35,  are  three  surface-sections,  taken  from  a  large 


*  The  writer  went  through   the  underground  workings  of  twenty-seven  of  the 
Bendigo  mines. 


THE   BENDIGO   GOLD-FIELD. 


25 


26  THE   BENDIGO   GOLD-FIELD. 

open  cut  behind  the  Victoria  Quartz  mine.  '  The  different  beds  of 
slate  and  sandstone  are  indicated.  In  Fig.  33  it  is  seen  how  quartz 
has  been  deposited  along  joint- fractures  in  the  sandstone.  Both 
Figs.  33  and  34  illustrate  the  behavior  characteristic  of  the  small 
quartz-veins  of  the  district.  In  Fig.  35,  A  A  is  a  quartz-vein  hav- 
ing a  vein  within  itself,  and  presenting  a  sort  of  banded  structure, 
which  indicates  that  it  underwent  fracturing  after  the  deposition  of 
the  first  quartz. 

CONCLUSION. 

The  above  notes,  scattered  among  the  several  mines  of  one  mining 
district,  indicate  the  infinite  variety  of  ore-deposition.  Perplexing 
as  such  differences  of  lode- formation  may  appear,  and  contradictory 
as  some  of  the  modes  of  go  Id -occurrence  may  seem,  there  is  no  doubt 
that  they  can  be  shown  to  be  the  harmonious  effects  brought  about 
by  the  same  set  of  causes,  and  due,  in  their  variety,  to  the  varying 
structural  conditions  and  relations  of  the  beds  of  slate  and  sand- 
stone in  which  they  are  found. 


f 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


THE  ORIGIN  OF  THE  GOLD-BEARING  QUARTZ  OF  THE 
BEND1GO  REEFS,  AUSTRALIA. 

BY  T.    A.    RICKARD,   DENVER,    COLORADO. 

(Chicago  Meeting,  being  part  of  the  International  Engineering  Congress,  August,  1893.) 

THE  lode-formation  of  the  Bendigo  gold-field  was  described  in  a 
former  paper.*  It  presents  a  striking  identity  of  arrangement  with 
the  general  geological  structure  of  the  region,  which  is  one  of  com- 
parative simplicity.  The  alternating  beds  of  slate  and  sandstone 
which  constitute  the  prevailing  country-rock  have  been  extremely 
contorted  ;  yet  notwithstanding  their  highly  developed  cleavage  it  is 
possible  to  discern  in  their  structure  the  evidences  of  original  sedi- 
mentation. Along  the  crests  of  the  waves  which  are  the  axes  of 
anticlinal  folds  occur  bodies  of  gold-bearing  quartz,  of  great  econom- 
ical importance,  which  the  miners  have  appropriately  termed  "sad- 
dles." They  are  more  extensive  in  strike  than  in  dip,  are  found  to 
occur  in  a  recognized  succession,  and  have  been  followed  by  a  very 
complete  system  of  mine-workings  reaching  from  the  surface  to  more 
than  half  a  mile  below. 

I.  THE  KOCK-FORMATIONS. 

At  the  commencement  of  our  inquiry  into  the  origin  of  this  gold- 
bearing  quartz,  it  will  be  necessary  to  consider  the  relative  ages  of 
the  different  formations  of  the  region.  Numerous*  graptolites  have 
made  it  easy  to  label  the  slates  and  sandstones  in  which  the  reefs 
occur  as  Lower  Silurian.  Any  further  subdivision,  however,  of 
this  great  thickness  of  rocks  has  been  rendered  almost  impossible  by 
reason  of  the  striking  lack  of  variety  in  the  fossil  remains,  the  gen- 
eral confinement  of  their  occurrence  to  the  slates ;  the  marked 
scarcity  of  conglomerates  and  breccias;  and  finally,  the  notable 
similarity  of  texture  and  composition  which  characterizes  the  succes- 
sive beds  of  slate  and  sandstone. 

The  enormous  thickness  of  this  series  has  been  referred  to.  Dr. 
A.  R.  C.  Selwyn,  at  one  time  head  of  the  geological  survey  of  Vic- 

*  "The  Bendigo  Gold-Field,"  Trans,  xx.,463. 
1 


ORIGIN    OF    GOLD-BEARING    QUARTZ    OF    BENDIGO    REEFS. 


toria,*  estimated  it  at  35,000  feet.  The  same  authority  is  in  accord 
with  the  present  government  geologist,  R.  A.  F.  Murray,  in  consid- 
ering that  a  thickness  of  7500  feet  of  superincumbent  rock  at  one 
time  covered  the  beds  which  now  form  the  surface. 

The  geological  map  of  the  colony  f  here  reproduced  (Fig.  1)  indi- 

Fig.  I. 


(j  IMT.HOPE  • 


"'l 


i  rmllry  $  1'uatcg  t.nyre.  A.  I'. 


ALE.    1^50    MILES 


GRANITE 

GEOLOGICAL   SKETCH    MAP 

OF  A    PORTION    OF 

VICTORIA. 

cates  that  the  Silurian  rocks  of  the  BendigoJ  gold-field  are  overlain 
to  the  north  by  Tertiary  shales,  while  south  they  abut  against  the 
granite  mass  of  Mount  Alexander,  which,  in  a  horseshoe  form,  sepa- 
rates this  mining  district  from  that  of  Castlemaine. 

The  contact  between  the  two  older  formations  is  best  seen  in  cer- 

*  Now  director  of  the  Geological  Survey  of  Canada. 

f  Taken  from   "Geological  and  Physical  Geography  of  Victoria,"  by  R.  A.  F. 
Murray. 

I  The  old  name  "  Sandhurst  "  appears  on  the  map  in  place  of  "  Bendigo." 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS.         3 

tain  road-cuttings  at  Big  Hill,  7  miles  from  the  town.  The  accom- 
panying map*  (Fig.  2)  shows,  on  a  scale  larger  than  that  of  the 
general  map,  the  principal  features  of  the  surface  geology  of  this 
part  of  the  district.  It  will  be  noticed  that  the  crest  of  the  ridge  is 
formed,  not  by  the  granite  but  by  the  Silurian  rocks  where  hard- 
ened by  their  contact  with  the  granite.  The  railway  passes  through 
the  ridge ;  but  the  tunnel  indicated  on  the  map  is  rendered  useless 
for  the  purpose  of  obtaining  a  geological  section  by  reason  of  the 


FIG.  2. 


POST  PLIOCENE 


GEOLOGICAL   MAP 

BIQ  HILL,  BENDiQO. 

brickwork  which  effectually  hides  the  rock- structure.  A  short  dis- 
tance to  the  west,  however,  the  main  wagon-road,  in  crossing  the 
hill,  affords  several  interesting  sections. 

The  northern  edge  of  the  cutting  shows  the  commencement  of  the 
physical  and  chemical  changes  produced  in  the  Silurian  rocks  by 
contact-metamorphism.f  The  slate  graduates  into  a  crystalline 
schist  and  the  sandstone  becomes  a  quartzite.  More  mica  has  been 

*  A  reproduction  of  a  small  part  of  a  general  map  of  the  gold-field,  published  by 
the  department  of  mines,  Melbourne. 

f  Also  termed  by  Daubre"e,  "  the  metamorphism  of  juxtaposition,"  page  133, 
Etudes  Synthetiques  de  Geologic  Experimentale. 


4         ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS. 

developed.  At  this  point  the  structure  of  the  country  shows  no 
marked  disturbance ;  but  in  approaching  the  highest  point  of  the 
road,  attention  is  drawn  to  a  distortion  of  the  bedding  by  the  occur- 
rence of  a  large  black  lava  dike,  which  evidently  follows  a  line  of 
fracture. 

Further  southward  the  rocks  begin  to  exhibit  more  marked  altera- 
tion, being  hardened,  somewhat  bleached,  and  very  much  jointed. 
At  the  crest  of  the  ridge  the  granite  itself  is  first  noticed.  (See  Fig. 
3.)  On  the  west  the  cutting  gives  a  partial  syncline,  the  members 
of  which  show  joints.  Underneath,  and  upon  a  level  with  the  road 
itself,  the  first  intrusions  of  granite  are  to  be  seen.  Small  veins  of 
it  extend  halfway  up  the  height  of  the  cutting.  The  rocks  forming 
the  immediate  foreground  of  the  sketch  are  cut  up  by  joints  and 
cross-joints.  The  bedding  is  indicated  by  the  contour  of  the  em- 
bankment which  forms  the  side  of  the  road. 

On  the  southern  slope  of  the  ridge  the  cleavage  of  the  slates  is 
very  marked,  and  the  sandstones  are  traversed  by  several  systems  of 
fracture,  while  both  rocks  have  become  hardened  and  more  brittle. 
The  granite  again  appears  in  the  form  of  small  veins  penetrating  the 
overlying  rocks.  (See  Fig.  4.)  The  vein  of  granite,  G,  intrudes 
among  a  series  of  thin  beds  which  have  been  so  altered  that  it  is 
difficult  to  recognize  which  of  them  were  originally  slate.  Two 
systems  of  joints,  C  C,  are  readily  noted,  more  particularly  in  the 
sandstones,  A,  A.  A  little  further  on,  the  gradually  diminishing 
sides  of  the  cutting  gave  the  section  reproduced  in  Fig.  5,  where  G, 
H  and  K  are  veins  of  granite  (2,  2J  and  15  inches  wide  respectively), 
which  have  noticeably  affected  the  sandstone  bed  A.  The  slates  B, 
B,  are  also  baked,  and  their  ordinary  cleavage  (60°  to  65°)  is 
largely  obliterated  by  cross-fracturing. 

The  wagon  road  does  not  show  the  actual  contact  of  the  two  forma- 
tions ;  but  the  railway,  in  approaching  the  tunnel  from  the  south, 
gave  me  the  sketch  seen  in  Fig.  6.  Here  the  main  mass  of  the 
granite  throws  out  small  branches  which  intrude  between  the  bed- 
ding-planes of  the  slates  and  sandstones,  penetrating  them  for  a  con- 
siderable distance.  Some  of  these  veins,  C  C,  are  not  more  than  a 
couple  of  inches  thick.  The  darker  lines,  B  B,  indicate  segregrations 
of  ironstone. 

Approaching  the  tunnel-entrance  a  crossing  of  two  granite  veins 
is  observed  (Fig.  7). 

To  the  facts  above  given,  the  following  observations  may  be  added. 
At  500  yards  from  the  contact  the  effects  produced  are  only  faintly 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS.         5 


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6         ORIGIN   OP   GOLD-BEARING   QUARTZ   OF    BENDIGO    REEFS. 

observable  in  the  occurrence  of  joints  recognized  as  not  habitual ;  at 
300  yards  the  fracturing  has  become  very  marked  and  the  rocks  have 
lost  their  usual  cblor.  Even  in  the  immediate  vicinity  of  the  contact 
the  bedding  of  the  Silurian  rocks  has  not  been  notably  disturbed. 
The  changes  produced  in  the  slates  and  sandstones  consist  in  their 
being  somewhat  bleached,  considerably  hardened,  and  very  much 
fractured. 

The  penetration  of  the  sedimentary  rocks  for  such  a  distance  from 
the  contact  by  such  small  veins  of  granite,  without  however  causing 
any  disturbance  of  the  bedding,  affords  a  study  of  peculiar  interest. 
To  explain  the  behavior  of  the  granite,  it  must  be  allowed  to  have 
been  in  a  mobile  condition.  Mobility  suggests  fluidity,  and  fluidity 
in  rocks  is  generally  held  to  be  the  result  of  a  molten  state.  An  acid 
rock  could  not,  however,  by  reason  of  heat  alone,  be  in  a  plastic, 
much  less  a  fluid  state,  except  at  an  extremely  high  temperature. 
That  temperature  has  been  approximately  determined  as  being  pro- 
bably more  than  2500°  but  less  than  3000°  F.  Mallet's  experi- 
ments *  on  siliceous  slags  proved  that  their  melting  point  was  about 
3000°  F.  Though  we  find  that  the  general  effects  of  heat  upon  the 
slates  and  sandstones  are  indeed  observable,  yet  the  actual  surfaces 
in  contact  with  the  granite  are  not  particularly  affected ;  and  the 
evidence  as  a  whole  strongly  indicates  that  no  such  temperature  as 
that  just  mentioned  could  have  existed  at  this  point. 

The  volcanic  phenomena  of  to-day  furnish  a  clue  to  the  problem 
here  suggested.  The  ejection  of  lava  from  volcanic  vents  is  accom- 
panied by  enormous  volumes,  not  of  smoke  but  of  steam.  The 
movement  of  a  lava-flow  down  the  mountain-side  is  marked  by 
those  clouds  of  watery  vapor  whose  after  condensation  precipitates 
the  heavy  rains  which  are  often  more  injurious  to  man  than  the 
desolation  caused  by  the  lava  itself.  The  subsequent  examination 
of  the  cold  lava  will  show  it  to  have  a  vesicular  structure  due  to 
the  myriad  bubbles  of  superheated  steam  which  it  contained  at  the 
time  of  ejection.  In  this  way,  by  the  aid  of  the  steam  which  forms 
a  large  part  of  their  bulk,  acid  lavas  are  often  as  mobile  and  ap- 
parently as  fluid  as  those  which  have  a  basic  composition.  More- 
over, Daubree  has  proved  that  siliceous  rocks  which  require  a  tem- 
perature of  2500°  to  3000°  F.  before  they  undergo  true  fusion  will 
yet  become  liquid  at  800°  F.  if  in  the  presence  of  superheated 
steam. 

*  Also  those  of  Sir  Lowthian  Bell. 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS.        7 

It  is  suggested,  therefore,  that  the  penetration  of  these  slates  and 
sandstones  for  some  distance  from  the  contact  by  small  veins  of 
granite  was  due  to  a  condition  of  suspended  solidification  caused  by 
the  presence  in  the  igneous  rock  of  imprisoned  steam,  taken  up  by 
the  intrusive  mass  of  granite  when  at  lower  depths.*  The  granite,  it 
is  true,  does  not  now  exhibit  a  vesicular  structure  such  as  would  or- 
dinarily characterize  a  rock  whose  mass  has  been  interpenetrated  by 
steam  ;  but  it  must  be  remembered  that  it  cooled  under  the  pressure 
of  a  great  thickness  of  overlying  formations  and  was  extruded  at  so 
early  a  period  in  geological  time  that  any  such  structure  would  long 
ago  have  been  obliterated  by  those  infinitely  slow  physical  and 
chemical  changes  which  are  forever  bringing  about  the  "  decay  and 
repair  "  of  rocks. 

To  the  petrographer  the  granite  presents  no  particular  feature  of 
interest.  It  is  of  the  normal  type,  consisting  of  mica,  quartz  and 
orthoclastic  feldspar. 

It  was  extruded  at  a  period  previous  to  the  Devonian,  but  later 
than  the  Lower  Silurian.  The  following  facts  warrant  this  state- 
ment. In  the  sections  afforded  by  the  road-cutting  and  railway- 
embankments  at  Big  Hill,  we  have  seen  that  it  intrudes  between  and 
across  the  bedding-planes  of  the  slates  and  sandstones.  It  must 
necessarily,  therefore,  be  of  later  origin.  Further,  while  the  great 
series  of  the  Lower  Silurian  rocks  has  been  much  folded  and  con- 
torted, yet  this  has  not  altogether  obliterated  the  original  lines  of 
their  sedimentation,  and  we  find  that  when  the  strike  of  the  slates 
and  sandstones  makes  an  acute  angle  with  the  locally  irregular  line 
of  the  contact,  their  dip  abuts  against  the  granite.  Viewed  as  a 
whole,  however,  the  general  line  of  the  contact  is  at  right  angles  to 
the  strike,  and,  therefore,  to  the  axes  of  the  folds  of  the  Silurian 
rocks.  This  fact  proves  not  only  that  the  granite  was  extruded  at  a 
period  following  the  deposition  of  the  Silurian  sediments,  but  also 
subsequently  to  that  folding  which  is  one  of  their  most  noteworthy 
features.  The  stratigraphical  position  of  the  granite  is  further  in- 
dicated by  the  fact  that  elsewhere  in  the  Colony  its  eroded  edges  are 
overlain  by  rocks  known  to  be  Devonian,  which  are  neither  pene- 
trated nor  altered  at  the  surface  of  contact. 

Fig.  8  f  represents  a  section  at  Mt.  Hump  Creek. 

*  Since  the  above  was  written  I  have  read  Rev.  Osmond  Fisher's  "  Physics  of  the 
Earth's  Crust,"  in  which  the  author  argues  in  favor  of  the  existence  beneath  the 
earth's  crust  of  a  liquid  substratum  of  rock  holding  water-vapor  in  solution. 

f  From  Geology  and  Physical  Geography  of  Victoria,  by  R.  A.  F.  Murray. 


8         ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS. 

Having  determined  the  relative  ages  of  the  slates  and  sandstones 
in  which  the  quartz-reefs  occur,  and  of  the  granite  with  which  the 
former  come  in  contact,  we  have  one  other  formation  to  consider.  I 
refer  to  the  lava  dikes,  incidental  references  to  which  have  been  fre- 
quently made  in  my  previous  papers  on  this  subject.  They  form  a 
marked  and  instructive  feature  of  the  Bendigo  mine-workings.  A  few 
additional  sketches  will  serve  to  illustrate  further  the  characteristic 
behavior  of  these  "  lava-streaks/7  as  the  miners  call  them.  This  is 

FIG.  8. 


A.  SILURIAN  B.  OrmrNJTE  C.  DEVONIAN 

well  shown  in  the  cross-section  of  the  deep  levels  of  the  1 80  mine. 
(Fig.  9.)  The  course  of  the  dike,  whose  width  averages  about  9 
inches,  can  be  readily  followed  as  it  cuts  through  the  successive  sad- 
dle-formations. In  Fig.  10  a  dike  (in  another  mine)  is  seen  to  tra- 
verse a  sandstone,  cutting  through  several  small  quartz-veins,  until 
it  reaches  a  bedding-plane,  which  it  then  follows.  In  Fig.  11  an- 
other lava-streak,  following  the  structural  lines  of  the  country-rock, 
becomes  "  pinched  out "  in  the  plane  of  the  section  along  which  the 
sketch  is  taken.  Doubtless  it  found  an  easier  passage  elsewhere.  In 
Fig.  12  a  larger  dike,  14  inches  wide,  exhibits  centers  of  decompo- 
sition marked  by  concentric  formations  of  white  zeolites.  There  is 
a  dark  band  of  less  altered  lava  following  the  center  of  the  dike.  In 
Fig.  13  a  lava-streak  separates  into  two  small  branches  before  finally 
dying  out. 

It  requires  but  little  observation  underground  to  determine  the 
recent  origin  of  these  dikes,  which  evidently  followed  a  passage  along 
those  lines  in  the  country-rock  offering  the  least  resistance. 

The  lava  is  of  Tertiary  age,  either  Pliocene  or  post-Pliocene.  It 
is  identical  in  lithological  character  with  the  basalt,  successive  sheets 
of  which,  in  a  manner  much  resembling  that  to  be  observed  in  Cali- 
fornia, overlie  the  Miocene  and  Early  Pliocene  gravel  of  the  "  deep 
leads"  of  the  alluvial  mines  of  Victoria.  The  gold-field  of  Ben- 
digo was  probably  also,  at  one  time,  covered  by  the  lava  extruded 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS. 


from  the  dikes ;  and  while  all  vestiges  of  such  an  outflow  have  since 
been  removed  by  erosion,  yet  by  a  comparison  of  its  structure,  com- 
position and  behavior  it  is  easy  to  see  the  similarity  existing  between 
the  rock  which  forms  the  "  lava-streaks  "  of  the  deep  workings  of 


I 


I 


the  mines  and  that  of  the  basaltic  plateaux  overlying  the  rich  allu- 
vium of  the  neighboring  districts  of  Clunes  and  Heathcote,  and  the 
more  distant  ones  of  Ballarat  and  Ararat. 

It  is  not  easy  to  determine  accurately  such  a  rock  as  the  Bendigo 


10      ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS. 

lava.  Igneous  rocks  in  the  vicinity  of  ore-deposits  are  almost  in- 
variably much  altered,  and  therefore  very  difficult  of  examination 
under  the  microscope.  In  the  case  of  a  basic  rock,  such  as  the  one 
under  consideration,  these  difficulties  are  very  much  increased. 
Upon  examining  a  fair  sample  of  the  lava,  taken  from  2000  feet 
below  the  surface,  Prof.  Judd,  F.R.S.,  at  the  Royal  School  of  Mines, 
London,  decided  that,  while  now  much  altered,  it  was  originally 
basaltic  in  character  and  contained  free  crystals  of  olivine  of  con- 
siderable size.  The  augite  and  magnetite  are  abundant  and  well 
preserved,  but  the  alu  mi  no-alkaline  constituent  of  the  rock  has 
almost  disappeared.  Leucite,  nephelite,  or  even  melilite  may  have 
been  present.  The  Germans  would  call  such  a  rock  "melaphyr,"  a 
term  which  Dana,*  however,  highly  disapproves. 

In  the  mines  the  lava  is  generally  far  advanced  in  decomposition. 
The  olivine  becomes  converted  into  serpentine.  The  vesicles,  often 
arranged  so  as  to  indicate  that  the  mass  has  flowed,  are  filled  with 
zeolites.  At  the  surface,  or  within  the  domain  of  surface-waters, 
this  alteration  has  of  course  progressed  even  further,  and  only  white 
soapy  clays  remain  to  contrast  with  the  black,  compact,  and  homo- 
geneous rock  of  the  deep  levels. 

One  feature  of  the  behavior  of  these  dikes  has  peculiar  interest, 
namely,  their  penetration  through  such  an  enormous  thickness  of 
overlying  rock.  In  the  180  mine  I  have  traced  from  the  surface  to 
a  depth  of  over  2600  feet  a  dike  only  9  inches  wide.  It  is  fair  to 
assume  that  the  dike  must  have  found  its  way  for  a  distance  many 
times  exceeding  that  for  which  it  can  be  actually  observed,  for  allow- 
ance must  be  made  for  the  portions  eroded  since  the  Tertiary 
period,  and  also  for  that  much  greater  unknown  depth  from  which 
the  lava  came. 

The  question  arises,  did  the  lava  effect  its  passage  slowly  or  was  it 
shot  upward  through  its  entire  length  and  height  in  one  instanta- 
neous operation  ?  The  latter  explanation  requires  the  formation  of 
a  continuous  fissure,  itself  unwarranted  by  the  facts  in  this  case,  and 
the  conception  of  its  instantaneous  filling  with  lava  along  its  entire 
extent  further  presupposes  that  the  material  of  the  dikes  remained 
molten  during  the  brief  time  of  such  a  performance.  Again,  the 
force  which  was  able  to  shoot  the  lava  upward  through  the  tortuous 
fractures,  penetrating  many  thousands  of  feet  of  overlying  rock, 
would  also  cause  it,  when  it  reached  the  surface,  to  be  ejected  with 
great  violence  and  to  a  great  height  into  the  air. 

*  Manual  of  Mineralogy  and  Petrography,  p.  485. 


ORIGIN   OF   GOLD-BEARING    QUARTZ    OF   BENDIGO    REEFS.      11 

Such  an  explanation  is  in  accord  with  the  catastrophic  theories  of 
the  past,  but  it  is  opposed  by  the  modern  study  of  volcanic  action, 
and  does  not  harmonize  with  the  facts  as  observed  in  the  mines  of 
Bendigo. 

The  accurate  observation  of  volcanic  phenomena  by  Scrope  and 
Judd*  has  shown  that  the  molten  material  issuing  from  the  vent  of 
a  volcano  usually  wells  up  slowly.  The  violent  paroxysmic  out- 
bursts which  do  occasionally  take  place  are  essentially  surface-occur- 
rences, and  are  due  to  a  sudden  relief  from  pressure  obtained  by  the 
escape  of  accumulated  superheated  steam. 

The  course  of  the  dikes  and  the  effect  of  the  lava  upon  the  rock- 
surfaces  in  contact  must  be  now  considered.  Nothing  in  their  mode 
of  occurrence  is  more  remarkable  than  their  tortuous  and  very  irreg- 
ular passage  through  the  overlying  rocks.  They  do  not  fill  a  clean- 
cut,  continuous  fissure;  they  rarely  preserve  a  straight  line  for  any 
great  distance,  but  follow  bedding-plane,  joint  and  cross-fracture,  as 
each  in  turn  presents  itself.  Where  their  line  of  passage  takes  them 
across  the  quartz-reefs,  the  crossing  is  generally  effected  near  the 
apex  of  the  saddle.  The  conclusion  arrived  at  is,  therefore,  that  the 
penetration  of  the  basalt  through  the  slates  and  sandstones  was  not 
the  work  of  a  few  seconds,  during  which  it  was  shot  upward  instan- 
taneously through  its  entire  height  and  length,  but  rather  that  it 
required  a  long  time,  and  took  place  during  a  period  when  the  Silu- 
rian rocks  were  subject  to  a  tangential  strain  which  caused  their 
fracturing  and  thereby,  little  by  little,  offered  a  passage  to  the  basalt, 
which  being  at  the  time  under  pressure,  was  seeking  its  way  upward. 

The  effects  produced  upon  the  Silurian  rocks,  through  which  at 
Bendigo  the  basalt  penetrates,  and  upon  the  granite  and  gravel,  upon 
which  in  the  neighboring  districts  it  lies,  are  in  each  instance  so 
slight  as  to  be  barely  observable.  The  feeble  changes  produced 
upon  the  rock-surfaces  in  contact  suggest  themselves  as  due  rather 
to  the  action  of  water  than  to  the  effects  of  heat. 

It  is,  indeed,  true  that  rocks  having  the  composition  of  these  ba- 
salts are  fluid  at  a  temperature  low  in  comparison  with  that  required 
to  melt  an  acid  lava;  but  observation  of  the  behavior  of  the  dikes, 
and  of  the  effects  produced  upon  the  beds  through  which  they  pass, 
impresses  one  with  the  conviction  that  the  temperature  of  the  mate- 
rial filling  them  did  not  reach  that  which  even  the  more  basic  of  basalts 
require  for  their  fusion.  The  conclusion  forces  itself  upon  us  that 

*  As  described  by  the  former  in  his  book  entitled  Volcanos,  and  by  the  latter  in 
his  Volcanoes. 


12      ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   KEEFS. 

the  basalt  of  the  "  lava-streaks"  did  not  owe  its  mobility  to  a  molten 
condition  arising  from  intense  heat.  The  government  geologist, 
Mr.  R.  A.  F.  Murray,  states  the  belief  that  the  dikes  were  "in  great 
measure  the  product  of  hydro-thermal  action."*  This  is  my  view 
also,  which,  more  definitely  expressed,  is  as  follows :  The  material 
of  the  dikes,  when  forcing  its  passage  through  the  Silurian  rocks, 
was  more  in  the  condition  of  a  boiling  mud  than  what  we  ordinarily 
imagine  as  the  state  of  a  liquid  basalt ;  its  mobility  was  due  not  so 
much  to  the  fact  that  it  was  basic  in  chemical  composition,  and  there- 
fore more  readily  fused,  but  because  of  the  superheated  steam  of 
which  it  was  full.  Such  imprisoned  steam  was  superheated  because 
originating  at  a  great  depth.  It  has  been  found  that  within  the  very 
restricted  limits  of  human  observation  heat  increases  with  depth. 
As  we  sink  through  the  earth's  crust  the  average  increment  of  heat 
is  at  the  rate  of  1°  F.  per  47  J  feet  of  descent,  f  Water  cannot  re- 
main a  liquid,  in  spite  of  increasing  pressure,  at  a  temperature  above 
that  of  its  critical  point.  This  was  first  determined  by  Caigniard 
de  la  Tour  to  be  773°  F.  More  recently,  however,  Battelli  proved^ 
that  it  was  364°  C.,  equivalent  to  687°  F.  Such  a  temperature, 
taking  the  mean  surface  temperature  to  be  50°  F.,  would  be  reached 
at  a  depth  of  about  30,000  feet.  In  areas  under  disturbance  and  in 
volcanic  regions  local  conditions  would  tend  to  raise  the  temperature 
and  consequently  to  diminish  the  depth  required  to  reach  the  horizon 
where  water  can  no  longer  remain  liquid.  A  depth  of  less  than 
25,000  feet  might  then  suffice.  In  the  gold-field  of  Bendigo  we  have 
to  deal  with  a  series  of  rocks  over  35,000  feet  thick.  The  basalt  of 
the  dikes  has  come  up  through  that  thickness,  and  consequently 
must  have  had  its  origin  at  a  depth  greater  than  that  required  to 
reach  the  temperature  of  the  critical  point  of  water.  Such  water  as 
it  contained  must  have  existed,  therefore,  as  water-vapor,  which,  as  it 
approaches  the  surface,  we  may  call  superheated  steam.  This  steam 
was  in  a  state  of  compression,  seeking  to  be  relieved  of  its  load,  and 
striving  to  go  where  only  that  load  could  be  lightened,  that  is,  up- 
ward. The  expansive  force  of  such  imprisoned  steam  rendered  it  a 

*  Op.  cit.,  p.  137. 

f  Sir  William  Thompson  (Lord  Kelvin)  estimated  it  at  1°  per  51  feet.  Prof. 
Prestwich  collected  530  observations  made  in  248  localities,  and  selecting  those 
only  in  which  the  necessary  precautions  had  been  taken,  found  the  average  to  be 
as  above  stated,  1°  per  47£  feet. 

J  At  Turin,  in  1890.  Strauss  gives  the  critical  point  as  370°  C.  and  A.  Najedin 
as  358°  C.  This  information  I  owe  to  Prof.  Hallock  and  to  Mr.  Carl  Barus. 


ORIGIN   OF  GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS.      13 

powerful  agent  in  assisting  the  basalt  to  force  its  slow  way  through 
the  crevices  and  fractures  of  the  overlying  rocks  until  relief  was 
obtained  at  the  surface.  The  lava  would  have  lost  some  of  its 
heat  and  moisture  by  contact  with  the  rock-faces  along  which  it 
passed,  but  having  a  temperature  much  above  the  lowest  tempera- 
ture of  hydro-thermal  fusion,  it  could  lose  much  heat  without  solidi- 
fication, and  was  therefore  enabled  to  arrive  at  the  surface  where  it 
probably  welled  forth  water,  steam  and  mud,  overspreading  the  older 
rocks  andft  the  later  gravel  with  one  of  those  sheets  of  basalt  which 
form  so  marked  a  feature  of  the  surface  geology  of  the  Colony  of 
Victoria. 

The  Silurian  rocks  form  the  Ultima  Thule  of  all  research  into 
the  geological  history  of  the  region.  Of  the  rock- masses  by  the 
disintegration  of  which  they  were  formed,  no  vestige  remains.  Their 
uniformity  of  structure  and  composition,  their  thin  bedding  and 
general  regularity,  their  wide  extent  and  great  thickness,  all  prove 
that  they  were  the  sediments  deposited  during  enormous  periods  of 
time  from  a  comparatively  shallow  ocean.  The  frequent  ripple- 
marks  now  observed  at  a  depth  of  many  hundred  feet  below  the 
surface  tell  of  estuarine  seas  and  shallow  reaches  of  water.  The 
absence  of  any  large  bodies  of  conglomerate  and  breccia  indicates  a 
continuity  of  uniform  conditions. 

If  the  members  of  this  great  series  of  beds  were  deposited  in 
water  of  a  generally  uniform  depth  then  it  follows  that  the  bed  of 
the  Silurian  ocean  must  have  undergone  a  subsidence  which  kept 
pace  with  the  rate  of  sedimentation.  The  subsidence  occurred  along 
a  certain  line  of  weakness  in  the  earth's  crust,  which  later  became 
the  longer  axis  of  a  trough-like  depression.  The  gradual  deepening 
of  that  depression  corresponded  with  the  slow  rate  at  which  it  was 
being  filled. 

As  each  layer  of  material  became  covered  by  another  it  began  to 
undergo  a  change;  as  the  superincumbent  mass  became  thicker  and 
heavier,  the  thin  slime  and  the  fine  sand  were  consolidated  by  pres- 
sure and  commenced  to  take  to  themselves  the  form  and  structure  of 
the  rocks  which  we  term  slate  and  sandstone. 

When  the  area  of  depression  had  been  loaded  with  a  thickness  of 
seven  miles  of  sediment,  subsidence  ceased  and  elevation  began. 
The  existence  of  so  great  an  accumulation  of  material  determined 
the  choice  of  this  part  of  the  earth's  crust  as  the  place  of  an  eleva- 
tory  movement.  The  lowermost  layers  of  sediment  were  subject  to 
an  enormous  pressure  whose  effect  was  to  cause  condensation  fol- 


14      ORIGIN   OF   GOLD-BEARING    QUARTZ   OF    BENDIGO    REEFS. 

lowed  by  contraction.  This  was  the  local  cause  which  started  the 
action  of  the  tangential  strains  due  to  the  general  compression  of 
the  earth's  crust.  This  compressive  strain  brought  about  the  fold- 
ing of  the  Silurian  sediments,  it  caused  them  to  be  gradually  ele- 
vated and  compelled  the  sea- waters  covering  them  to  recede  slowly. 
Their  upper  portions  became  dry  land,  and  erosion  at  once  com- 
menced. 

The  forces  still  at  work  continued  to  exert  a  lateral  compression 
upon  the  sediments  which  now  had  become  rock-masses.  The  effects 
are  seen  in  their  highly  developed  cleavage  and  in  the  flexures  and 
undulations  which  are  to-day  their  most  marked  feature.  Their  cor- 
rugation made  them  stronger  but  less  pliant. 

Though  bent  and  folded,  the  Silurian  beds  were  not  at  this  time 
broken  by  extensive  fissures.  This  was  prevented  by  their  great 
thickness  and  by  their  comparative  flexibility.  That  flexibility  was 
due  in  the  first  place  to  the  water  which  they  still  held  over  from 
the  period  of  their  sedimentation,  and  secondly  to  their  fine  grain 
and  thin  bedding. 

The  neighboring  rock-masses,  forming  the  rim  of  the  original 
area  of  depression,  were,  however,  unprotected  by  any  such  depth 
of  overlying,  deposits;  they  were  older  and  more  rigid;  and  they 
became  consequently  broken  by  fractures  and  fissures  through  which 
volcanic  agencies  found  a  vent.  It  was  then  that  the  plutonic  gran- 
ite, perhaps,  absorbing  into  its  mass  the  lowermost  portions  of  the 
Silurian  beds,*  welled  up  toward  the  surface,  giving  out  its  heat  as  it 
advanced.  The  granite  as  it  was  extruded  must  have  exerted  a 
certain  pressure  against  the  slates  and  sandstones.  It  may  have 
been  the  agent  which  caused  those  minor  transverse  undulations 
whose  axes. are  at  right  angles  to  the  main  ore-bearing  anticlinal 
axes  of  the  Bendigo  gold-field. 

A  period  of  comparative  quiet  followed.     The  Silurian  rocks  un- 

*  At  Mt.  Tarrangower  there  is  an  inlier  of  sandstone  which  suggests  this.  For 
the  following  particulars  I  am  indebted  to  Prof.  Ulrich,  of  New  Zealand :  "  The 
Silurian  inlier  lies  about  16  chains  away  from  the  Granite-Silurian  boundary,  form- 
ing a  small  hillock  about  one  acre  in  extent.  It  consists  of  a  nearly  black,  dense, 
metamorphic  sandstone,  and  its  boundary  with  the  granite  can,  in  several  places 
round  its  circumference,  plainly  be  seen,  but  there  is  no  change  in  the  rock  other 
than  that  feldspar  particles  make  their  appearance  near  the  boundary.  However, 
in  a  water-course  which  cuts  across  the  contact  the  dark  Silurian  rock  can  in  one 
place  be  seen  to  run  down  into  the  granite;  and  there  it  becomes  gradually  quite 
light-colored,  i  e.,  strongly  feldspathic  and  also  micaceous  ;  in  fact,  so  altered  that 
any  geologist  seeing  a  hand-specimen  of  it  would  no  doubt  call  it  a  fine-grained 
granite." 


ORIGIN    OF    GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS.      15 

derwent  denudation  ;  their  upper  portions  were  disintegrated  ;  from 
their  debris  other  formations  were  built  up,  to  be  in  turn  eroded  and 
washed  into  the  waters  of  the  ocean.  While  the  upper  earth  was 
undergoing  change,  the  under  world  was  also  the  scene  of  silent 
chemical  and  physical  processes,  removing  matter  here  and  laying  it 
down  there,  destroying  and  upbuilding,  ever  shifting  their  centers 
of  activity  but  never  at  rest.  In  the  latter  part  of  the  Tertiary 
period  the  basaltic  lava  found  its  passage  through  the  fractures 
traversing  the  Silurian  rocks  and  covered  the  golden  alluvium 
lying  upon  their  eroded  edges. 

II.  THE  AURIFEROUS  QUARTZ. 

The  origin  of  the  deposits  of  gold-bearing  quartz,  belongs  to  no 
particular  period.  The  agencies  which  brought  the  ore  of  the  reefs 
to  its  present  position  began  to  operate  when  first  the  sediments  of 
the  Silurian  seas  were  laid  down,  and  have  continued  until  now. 

In  the  reefs  of  Bendigo  the  two  most  important  substances  are, 
the  metal,  gold,  and  the  matrix  quartz.  The  other  mineral  con- 
stituents found  in  association  with  these  two  are  relatively  unim- 
portant. Their  origin  is  a  matter  of  much  interest  but  it  can  be 
discussed  apart. 

1.   The  Quartz. 

The  Silurian  sediments  contained  a  large  proportion  of  sand,  and 
the  resulting  rocks  are  very  siliceous.  Silica  occurs  in  the  rocks 
partly  in  a  free  state,  as  quartz,  but  a  proportionally  larger  amount 
is  found  combined  as  a  silicate.  Free  quartz  is  soluble  in  heated 
waters.  The  quartz  combined  in  the  more  complex  form  of  silicates 
has  been  demonstrated  by  Daubree  and  others  to  be  readily  dis- 
solved in  hot  water,  more  particularly  superheated  steam. 

The  formation  of  the  quartz  lodes  has  taken  place  in  two  stages, 
namely,  leaching  followed  by  precipitation.  In  both  operations 
water  was  a  necessary  factor.  It  is  the  all-powerful  disintegrating 
and  transporting  agent  of  the  land-surface,  where  its  chemical  ac- 
tivity is  intensified  by  the  presence  of  dissolved  carbonic  acid;  it  is 
also,  though  in  a  different  way,  no  less  efficient  underground  where 
by  reason  of  the  prevalence  of  a  higher  temperature  it  becomes  more 
energetic  both  physically  as  a  force  and  chemically  as  a  reagent ;  and 
finally  it  is  increasingly  powerful  at  great  depths  where  even  the 
tremendous  pressure  of  superincumbent  rock-masses  will  not  prevent 
it  from  being  transformed  into  steam  and  developing  a  chemical 
activity  to  which  the  mineral  constituents  of  the  rocks  can  offer  but 


16      ORIGIN   OF    GOLD-BEARING    QUARTZ   OF   BENDIGO    REEFS. 

feeble  resistance.  It  was  the  agent  which,  from  a  state  of  general 
distribution,  collected  the  quartz  and  brought  it  into  the  fractures 
and  fissures,  crevices  and  cavities  where  the  miner  now  finds  it. 

All  rocks,  though  compressed  and  dried  as  they  appear,  contain 
moisture.*  All  rocks  are  pervious  to  waterf  to  a  varying  extent  by 
reason  of  capillary  action,  and  all  rock-masses  are  permeable  because 
of  the  fractures  and  joints  which  traverse  them.  It  has  been  shown 
by  Daubree,  Bischof  and  others,  that  only  a  very  small  quantity  of 
water  such  as  we  find  the  rocks  actually  to  contain  is  required  to 
produce  the  most  pronounced  changes  in  their  chemical  constitu- 
tion, particularly  when  aided  by  pressure,  accompanied  by  high 
temperature. 

The  heat,  in  most  instances  accompanied  by  pressure,  required  to 
make  the  water  in  the  rocks  intensely  active,  was  afforded  at  various 
times  and  for  long  periods.  At  the  earliest  stage  of  their  history 
they  were  subjected  to  high  temperature.  From  the  moment  that 
one  layer  of  sediment  was  deposited  on  the  ocean  bed  and  became 
covered  by  another  it  began  to  acquire  a  more  elevated  temperature 
in  consequence  of  its  increased  distance  from  the  surface  of  radiation. J 
As  the  thickness  of  the  sediments  kept  pace  with  the  sinking  of  the 
bottom  of  the  depression  in  which  they  were  laid,  the  successive 
beds  acquired  a  temperature  proportioned  to  their  depth.  The 
lowermost  members  attained  a  distance  of  over  35,000  feet  from  the 
surface.  Though  the  increment  of  temperature  be  not  constant  with 
increasing  depth, §  yet  the  heat  which  obtained  at  a  horizon  seven 
miles  from  daylight  must  have  been  extremely  high.|| 

The  great  thickness  to  which  they  attained  caused  an  enormous 
pressure  to  be  exerted  by  the  upper  upon  the  lower  members  of  the 
series.  Pressure  does  not  develop  heat  unless  motion  also  occurs. 
When,' however,  at  the  close  of  the  period  of  their  deposition  certain 
elevatory  movements  took  place,  their  great  thickness  must  have 
helped  to  develop  an  energy  which  became  converted  into  an  exceed- 

*  The  French  call  it  eau  de  constitution.  They  also  have  a  term  eau  de  carriere, 
which  is  the  equivalent  of  our  "quarry-water." 

f  The  amount  of  water  in  the  rocks  and  their  porosity  has  been  measured  by 
Sterry  Hunt,  Prestwich,  Delesse,  and  others.  See  Chemical  and  Geological  Essays 
by  the  first  and  Geology,  Chemical,  Physical  and  Stratigraphical,  by  the  second. 

J  An  observation  due  to  Babbage,  and  quoted  by  Daubree. 

\  See  Kev.  Osmond  Fisher's  Physics  of  the  Earth's  Crust,  1889,  chap.  i. 

||  Le  Conte,  Elements  of  Geology,  p.  93,  says,  "  the  lower  portion  of  sediments  10,000 
feet  thick  would  be  raised  to  a  temperature  of  about  260°,  and  of  40,000  feet  thick 
to  that  of  860°."  In  the  instance  under  discussion  the  eroded  portions  of  the  Silu- 
rian sediments  are  estimated  to  have  been  7500  feet  thick,  and  their  total  original 
thickness  to  have  been  35,000  feet. 


ORIGIN   OF   GOLD-BEARING    QUARTZ   OF    BENDIGO    REEFS.      17 

ing  heat.  This  period  of  elevation  and  corrugation  was  long;  and 
during  its  prevalence  the  slates  and  sandstones  must  have  been  sub- 
ject to  the  full  play  of  those  slow  chemical  and  physical  forces  which, 
though  less  striking  than  violent  volcanic  outbursts  and  sudden 
earth-movements,  are  yet  the  most  powerful  of  the  agencies  which 
modify  the  rocks. 

Afterwards,  when  the  granite  was  extruded,  further  heat  was 
diffused  through  the  adjoining  slates  and  sandstones.  In  the  long 
interval  which  separated  the  time  of  the  extrusion  of  the  granite 
from  that  which  marked  the  ejection  of  the  basalt,  the  Silurian  rocks 
were  subjected  to  slow  movements  of  elevation  and  depression  which, 
while  not  so  energetic  as  those  which  took  place  at  the  beginning  of 
their  life-history,  were  yet  sufficient  to  develop  a  rise  of  temperature. 
In  later  times,  the  period  during  which  the  lava  penetrated  the  older 
rocks  must  have  been  marked  by  an  increase  of  their  heat.  Though 
the  extrusion  of  both  granite  and  basalt  have  left  more  striking  evi- 
dence of  their  occurrence  than  the  slower  movements  referred  to, 
which  took  place  at  other  periods,  yet  the  heat  they  afforded  was  not 
so  widely  diffused,  and  the  effects  produced  were  comparatively  local. 
The  heat  given  out  by  both  granite  and  basalt  was  however  sub- 
sequently widely  distributed. 

This  distribution  was  effected  through  their  contact  with  under- 
ground waters  which,  becoming  converted  into  steam,  transferred 
some  of  their  heat  to  other  circulating  waters,  and  these  in  turn  in- 
jected their  heat  and  steam  through  the  pores  and  crevices  of  the 
slates  and  sandstones. 

The  hot  water  and  superheated  steam  *  thus  produced  during 
long  continuing  periods  were  the  restless  agents  in  leaching  the  rocks, 
in  dissolving  out  the  silica  from  its  state  of  combination  and  in  after- 
wards transferring  it  to  underground  currents  which  bore  it  away 
until  changed  conditions  compelled  them  to  deliver  it  up  by  preci- 
pitation as  quartz. 

Thus,  in  this  and  other  ways,  the  quartz  became  separated  out 
through  the  pores  of  the  rocks  by  a  kind  of  sweating  process,f  to 
be  segregated  along  the  joints  and  fractures  traversing  them. 

*  One  feels  inclined  to  speak  of  "superheated"  water,  but  there  is  no  such  thing. 
Superheated  water,  without  reference  to  pressure,  is  steam.  Geikie,  though  his 
writing  is  generally  a  model  of  accurate  expression,  slips  into  the  use  of  this  term 
on  page  284,  Text-book  of  Geology. 

f  Or,  as  Daubree  puts  it :  "  Le  quartz  a  e"te  fourni  aux  veines  par  une  sorte 
d'exsudation  de  la  roche  encaissante." 

2 


18      ORIGIN   OF   GOLD-BEARING    QUARTZ   OF   BENDIGO   REEFS. 

The  experiments  of  Daubree  proved  the  action  of  superheated 
steam  in  dissolving  the  silicates  and  the  subsequent  precipitation, 
upon  the  lowering  of  the  temperature,  of  crystalline  quartz  of  a 
character  similar  to  that  found  in  association  with  the  gold  and  other 
metals  of  ore-deposits. 

The  changed  conditions  compelling  precipitation  were  very  vari- 
ous in  kind  and  due  partly  to  physical,  partly  to  direct  chemical 
causes.  In  traversing  the  minute  underground  passages  of  the  rocks, 
the  hot  solutions  would  meet  with  portions  of  loose  or  crushed  rock, 
giving  larger  space,  increased  surface,  and  diminished  pressure. 
This  would  favor  precipitation.  The  workings  of  mines  often  afford 
illustrations  of  ore-deposits  which  owed  their  existence  to  such  con- 
ditions. Similarly  hot  waters  meeting  and  mingling  with  colder 
currents  or  passing  between  comparatively  cool  rock-surfaces  would 
have  their  solvent  power  diminished,  leading  directly  to  the  depo- 
sition of  the  material  in  solution.  The  hot  springs  of  the  present 
day  in  many  parts  of  the  world  give  us  familiar  examples  of  the 
precipitation  of  silica  resulting  from  the  lowering  of  the  tempera- 
ture of  the  issuing  waters.  A  third  cause  may  be  quoted.  The  re- 
ducing agency  of  organic  and  other  matter  is  able  to  precipitate 
silica  from  its  state  of  solution  as  a  silicate.  Of  this,  silicified  wood 
is  a  familiar  illustration. 

The  seas,  the  rivers,  the  thermal  springs,  and  the  underground 
waters  of  to-day  carry  notable  quantities  of  silica  in  solution.  Forch- 
ammer  found  sea-water  to  contain  silica,  and  in  certain  samples  he 
determined  the  quantity  to  be  as  much  as  3  parts  in  1,000,000  parts 
of  water.  A  cubic  mile  of  the  ocean  would,  at  this  rate,  contain 
13,500  tons  of  silica.  Deville  showed  that  the  river  Loire,  at  Or- 
leans, contained  in  100,000  parts  13.46  of  solid  matter,  of  which  30 
per  cent,  was  silica.  The  geysers  of  the  Yellowstone  Park,  those  of 
California,  Iceland,  and  the  north  island  of  New  Zealand,  all  de- 
posit silica  from  the  waters  ejected  by  them.  Steamboat  Springs,  in 
Nevada,  and  Sulphur  Bank,  in  California,  may  also  be  instanced. 
The  occurrence  in  New  Mexico  and  Arizona  of  extensive  areas  which 
have  undergone  submergence,  and  whose  forests  have  become  pet- 
rified by  the  action  of  percolating  siliceous  solutions,  affords  a 
striking  instance  of  the  transference  of  silica  by  underground  waters 
and  its  precipitation  under  favorable  conditions.  That  the  waters  of 
mines  contain  silica  in  solution  has  been  proved  by  the  silicificatiou* 

*  This,  as  pointed  out  to  me  by  Prof.  Le  Conte,  is  a  double  process,  consisting  of 
the  filling  of  the  interstices  by  the  precipitation  of  silica  and  the  actual  replacement 
of  the  woody  fiber  itself. 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS.      19 

of  drift-wood,  beautiful  specimens  of  which  have  been  found  in  tho 
auriferous  gravels  of  the  "  deep  leads  "  of  California  and  Australia. 
Such  silicified  wood  has  also  been  shown  to  be  gold-bearing. 

The  concentration  of  quartz  in  one  place  rather  than  in  another, 
its  deposition  between  certain  beds  and  along  certain  fractures  rather 
than  elsewhere,  are  the  results  more  of  simple  physical  conditions 
than  of  complicated  chemical  reactions,  and  are  due  to  causes  to  be 
discussed  in  considering  the  structural  geology  of  this  district. 

2.   The  Gold. 

The  waters  of  the  ocean  contain  gold.  In  1851  Malaguti  and 
Durocher  determined  the  occurrence  of  silver,  but  did  not  extend 
their  inquiries  into  the  question  of  the  presence  of  gold  in  sea- 
water.  This  fact  was  first  accurately  determined  by  Sonstadt  in 
1872.*  His  experiments  were  not  quantitative,  but  he  stated,  in 
parenthesis,  that  the  amount  was  "certainly  less  than  1  grain  in  the 
ton."f  More  recently,  however,  Miinster  found  an  average  of  5 
milligrammes  per  ton.J  In  endeavoring  to  arrive  at  an  approximate 
estimate  it  must  be  remembered  that  local  conditions,  such  as  the 
temperature  of  the  water,  will  affect  the  amount  in  solution.  Son- 
stadt's  researches  were  made  with  water  obtained  near  Ramsey,  in 
the  Isle  of  Man,  while  Miinster  got  his  from  the  Kristiania  Fjord. 
In  each  case  the  sea-water  was  that  of  a  northern  latitude.  In 
warmer  regions  it  is  probable  that  precipitation,  due  to  the  presence 
of  putrescent  organic  matter,  may  diminish  the  amount  of  gold 
held  in  solution. §  Let  us,  however,  take  5  milligrammes  (equiva- 
lent to  y1^  of  a  grain)  as  an  approximation.  This,  though  in  itself 
a  minute  quantity,  will  be  found  to  represent  an  enormous  total 
amount  of  gold  in  the  waters  of  the  ocean.  From  the  results  ob- 
tained from  the  careful  soundings  carried  out  by  the  Challenger  and 
similar  scientific  expeditions,  it  has  been  computed  that  the  ocean  has 
an  average  depth  of  2500  fathoms,  and  that  it  contains  400  million 
cubic  miles  of  water.||  This  is  equivalent  to  about  1 ,837,030,272,000 

*  "On  the  Presence  of  Gold  in  Sea-Water,"  E.  Sonstadt,  Chemical  News,  Oct.  4, 
1872,  xxvi.,  p.  159. 

f  Sonstadt  is  often  incorrectly  quoted  as  having  shown  that  sea-water  contains  1, 
grain  of  gold  per  ton. 

J  The  amount  of  silver  was  determined  to  be  20  mg.  per  ton.  See  "  On  The  Pos- 
sibility of  Extracting  the  Precious  Metals  from  Sea- Water,"  Journal  of  the  Society  of 
Chemical  Industry,  April  30, 1892,  xi.,  p.  351 ;  abstract  from  Norsk  Tekniak  Tidsskrift, 
vol.  10,  No.  1.  §  See  note  in  the  Chemical  News,  Oct.  4,  1872,  xxvi.,  p.  161. 

||  Geikie's  Text-book  of  Geology,  2d  ed.,  p.  33. 


20      ORIGIN    OF   GOLD-BEARING   QUARTZ    OF   BENDIGO    REEFS. 

million  tons,  which,  upon  the  basis  of  5  milligrammes  per  ton, 
would  represent  10,250  million  tons  of  gold.  By  way  of  contrast, 
it  may  be  added  that,  according  to  Soetbeer,  Leech,  and  others, 
the  gold-production  of  the  world,  from  the  beginning  of  149-5  to 
the  end  of  1892,  a  period  of  exactly  four  centuries,  has  amounted  to 
only  5020  tons.  The  present  output  is  equal  to  about  200  tons  per 
annum.* 

The  gold  in  sea-water  is  kept  in  solution  as  an  iodide,  f  The 
amount  of  free  iodine  present  in  the  ocean  is  very  minute ;{  but  a 
large  proportion  of  that  element  occurs  combined  as  an  iodate  of 
calcium. §  From  the  results  of  a  series  of  six  experiments,  Sonstadt 
found  that  a  cubic  mile  of  sea-water  contains  about  17,000  tons  of 
iodate  of  calcium  or  11,072  tons  of  iodine.||  This  represents  the 
occurrence  in  the  entire  ocean  of  no  less  than  4,428,800  million  tons 
of  iodine. 

The  iodine  which  maintains  the  gold  in  solution  is  obtained  from 
the  iodate  of  calcium.  Gold  is  soluble  in  extremely  dilute  solutions 
of  iodine,  which  under  ordinary  conditions  are  in  turn  readily 
reduced  by  organic  matter.  That  the  gold  in  the  sea  is  not  precipi- 
tated is  due  to  the  presence  of  the  iodate  of  calcium  in  which  it  is 
not  soluble  but  which,  being  readily  decomposed  by  putreseible  or- 
ganic matter,  liberates  the  iodine  required  to  keep  the  gold  in  solu- 
tion. 

There  is  reason  to  believe  that  the  sea- waters  of  to-day  contain 
much  less  iodine  than  those  of  former  geological  periods. ^[  That 
there  is  so  little  free  iodine  in  the  ocean  is  due  to  causes  parallel  to 
those  which  bring  about  the  noteworthy  absence  of  carbonate  of 
lime.  Marine  animals  abstract  the  latter  while  marine  plants  absorb 
the  former.  How  great  is  the  work  done  in  this  way,  is  evidenced 
by  the  dimensions  of  the  coral  reefs  and  by  the  Extent  of  the  forami- 
niferous  and  other  marine  limestones. 

The  abstraction  of  iodine  is  no  less  striking.  Sea-weeds,  and 
more  particularly  those  which  grow  at  great  depths,  are  the  chief 
source  of  the  iodine  of  commerce.**  When,  after  a  storm,  such  sea- 

*  The  colonies  of  Australasia,  since  1851,  have  produced  2830  tons,  of  which 
Bendigo  contributed  375  tons. 

f   The  Chemical  News,  October  4,  1872,  xxvi.,  p.  159. 

J  /^W.,  April  26,  1872,  xxv.,  p.  196. 

\  Ibid.,  April  26,  1872,  p.  197. 

||  Ibid.,  May  24, 1872,  p.  242. 

If  Thomas  Sterry  Hunt,  Chemical  and  Geological  Essays,  p.  142. 

**  It  is  also  recovered  from  the  nitrate  of  Chili. 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS.      21 

weeds  are  cast  upon  the  shores  of  Great  Britain,*  France  and  Swe- 
den, they  are  collected  and  burnt,  and  from  their  fused  ashes,  termed 
"  kelp,"  the  iodine  is  subsequently  extracted  by  a  simple  chemical 
process.  From  13,000  kilos  of  kelp  about  100  kilos  of  sodium  car- 
bonate and  15  kilos  of  iodine  are  obtained. f 

That  iodine  is  not  now  so  plentiful  in  the  sea  as  during  former 
geological  periods  has  been  suggested  by  chemical  investigations  into 
the  composition  of  rocks.  Certain  sedimentary  formations  contain 
notable  quantities  of  it.  It  has  been  found  in  some  aluminous  shales 
in  Sweden,  and  also  in  certain  varieties  of  coal  and  turf.J  The 
saline  waters  of  several  springs  contain  large  amounts  of  it.  Even 
rain-water  has  been  known  to  give  a  recognizable  iodine  reaction 
when  tested,  such  iodine  having  been  obtained  by  the  agenc}*  of 
winds  which  have  been  blowing  over  certain  areas  of  the  sea  where 
it  was  being  liberated  by  the  action  of  organic  matter  upon  the  iodate 
of  calcium. § 

Let  us  now  return  to  Bendigo.  The  conditions  which  prevailed 
during  the  time  when  the  Silurian  seas  washed  the  earth's  surface, 
were  no  less  favorable  to  the  solution  of  gold  than  those  which  ob- 
tain to-day.  It  is  indeed  probable  that  the  waters  of  the  paleozoic 
ocean  contained  more  gold  than  those  of  the  present  geological 
period.  When  the  sediments  sunk  to  the  bottom  they  carried  with 
them,  entangled  amid  the  silt  and  sand,  a  large  proportion  of  sea- 
water,  most  of  which  was  subsequently  yielded  up  as  they  were 
pressed  down  by  the  weight  of  the  overlying  deposits.  The  sea- 
water  as  it  was  rejected  by  the  solidifying  strata,  left  behind  it  a  re- 
siduum which  contained  in  a  highly  concentrated  form  the  original 
constituents  of  the  Silurian  ocean.  The  sediments  which  fell  to  the 
ocean  floor  also  contained  portions  and  fragments  of  vegetable  life 
which  in  their  decay  served  to  decompose  the  iodate  of  calcium  con- 
tained in  the  residual  sea- water  and  so  set  free  the  iodine.  This  is 
a  very  active  element  and  would  at  once  form  a  fresh  combination. 
The  excess  of  iodine  thus  obtained  may  have  served  as  a  solvent  for 
any  particles  of  metallic  gold  which  by  mechanical  means  accompa- 
nied the  sands  laid  down  beneath  the  sea  and  which  thus  became 
added  to  that  already  derived  from  original  chemical  solution  in  the 
waters  of  the  ocean. 

*  Particularly  the  western  isles  of  Scotland,  and  the  west  coasts  of  Wales  and 
Cornwall. 

f  The  Principles  of  Chemistry,  D.  Mendeljeff,  vol.  i.,  p.  490. 
J  Fownes's  Chemistry,  p.  185.       \   The  Chemical  News,  May  17, 1872,  xxv.,  p.  231. 


22      ORIGIN   OF  GOLD-BEARING   QUARTZ   OF   BENDIGO    REEFS. 

The  great  body  of  slates  and  sandstones,  not  less  than  seven  miles 
in  thickness,  was  thus  slightly  but  distinctly  gold-bearing.  It  is 
so  still ;  the  amount  of  the  precious  metal  has  remained  practically 
the  same  and  the  changes  which  have  occurred  have  merely  brought 
about  its  less  uniform  distribution. 

As  the  sediments  were  further  consolidated,  the  vegetation  which 
they  originally  contained  became  disintegrated  into  its  elements,  and 
the  iodine  which  it  had  abstracted  from  the  sea-water  when  alive 
was  now  yielded  up.  The  iodine  thus  derived  became  another  fac- 
tor in  the  solution  of  the  gold  which  was  disseminated  through  the 
solidifying  strata. 

From  a  state  of  eveii  dissemination  through  great  rock-masses  to 
its  concentration  along  certain  lines  of  fracture  which  we  call  reefs, 
the  gold  arrived  through  the  agency  of  the  water  still  retained  by 
those  rock- masses.  The  geological  history  of  the  district  has  shown 
that  from  various  causes  the  heat  required  to  make  those  underground 
waters  intensely  active  was  at  hand  for  long  periods.  It  is  probable 
that  the  time  of  the  extrusion  of  the  granite  was  in  this  respect  one 
of  unwonted  chemical  activity.  So  also  was  the  later  period,  when 
the  lava  dikes  penetrated  the  overlying  strata. 

As  an  iodide,  the  gold  readily  circulated  through  the  medium  of 
the  waters  occurring  in  the  rocks.  We  know  gold  to  be  readily 
soluble,  even  in  extremely  dilute  iodide  solutions.  It  would  be 
wrong,  however,  to  suppose  that  this  or  any  other  one  chemical 
agency  was  the  universal  solvent  for  the  precious  metal.  There  is 
reason  to  suppose  that  in  different  formations  and  under  diverse  con- 
ditions gold  is  soluble  in  varying  combinations,  all  having  a  common 
want  of  stability.  It  has  been  suggested  by  Le  Conte  and  others, 
and  some  recent  discoveries*  in  the  mines  have  tended  to  confirm  the 
supposition,  that  the  gold  of  certain  lodes  has  been  deposited  from 
the  solutions  of  the  persulphate  of  iron.  Alkaline  sulphides. have 
long  been  mentioned  in  the  text-books  as  the  chief  agents  in  the  dis- 
solving of  the  metallic  sulphides,  and  very  pretty  chemical  formulae 
have  been  evolved  to  explain  the  resulting  complicated  reactions.f 

*  "Gold  Deposits  in  the  Quartzite  Formation  of  Battle  Mountain,"  F.  Guiterman, 
Proceedings  of  the  Colorado  Scientific  Society,  vol.  iii.,  part  iii. 

f  The  supposition  that  gold  is  insoluble  in  alkaline  sulphides  requires  modifica- 
tion. At  the  June,  1893,  meeting  of  the  Colorado  Scientific  Society,  Mr.  L.  G. 
Eakins  reported  the  results  of  recent  experiments,  which  show  that  fine  gold, 
digested  for  four  to  five  days  in  a  cold,  strong  yellow  solution  of  ammonium  sul- 
phide, has  a  solubility  equal  to  2  per  cent.  Weak  solutions,  with  seven  days'  diges- 
tion, gave  confirmatory  results.  Sodium  sulphide  also  was  found  to  be  a  solvent. 


ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS.      23 

Occasionally  gold  is  found  free  from  association  with  metallic  sul- 
phides ;  then  Bischof  's  experiments  are  quoted,  and  its  origin  is  put 
down  to  a  silicate  of  gold  soluble  in  alkaline  waters.  Again,  gold 
readily  combines  with  free  chlorine,  forming  a  salt  easily  soluble  in 
water.  The  chloride  of  gold  has,  however,  not  been  considered  as 
likely  to  exist  in  nature  because  of  the  rarity  of  the  occurrence  of 
free  chlorine  and  because  of  the  instability  of  the  compound  which 
it  forms  with  gold.  The  latter  quality  is  not  peculiar,  but  charac- 
teristic of  all  the  salts  of  gold  as  we  know  them.  Free  chlorine 
does  exist  in  nature,  and  though  not  frequently  detected,  this  is  not 
to  be  wondered  at,  seeing  that  its  occurrence  is  usually  associated 
with  that  of  hot  water  or  steam.  Volcanoes,  especially  during  times 
of  temporary  quiescence,  emit  large  quantities  of  hydrochloric  acid,* 
and  the  rims  of  the  volcanic  vents,  then  called  "fumaroles,"  show 
incrustations  of  chloride  of  iron,  chloride  of  ammonium,  etc.  The 
comparatively  large  amounts  of  such  salts  as  exist  in  sea- water,  which 
were  found  at  Vesuviusf  was  one  of  the  facts  used  in  support  of  the 
theory  that  the  steam  of  volcanic  eruptions  came  from  the  ocean. 
That  these  and  other  compounds,  including  hydrochloric  acid,  owe 
their  origin  to  free  chlorine,  and  were  formed  in  the  presence  of  hot 
water  and  steam,  is  most  probable.  Therefore  it  would  seem  well 
to  add  the  chloride  to  the  other  probable  combinations  in  which  gold 
may  circulate  underground. 

In  the  great  laboratory  of  nature,  the  chemical  changes  which  take 
place  in  the  long  periods  of  time  with  which  we  have  to  deal  must 
be  of  an  infinite  variety,  and  therefore  no  number  of  chemical  formu- 
la can  represent  the  reactions  which  have  followed  each  other  from 
the  moment  when  the  -gold  was  liberated  by  the  disintegration  of 
some  pre-Silurian  rock  to  this  later  day,  when  the  miner  finds  it  en- 
closed in  the  quartz  of  the  reefs.  Therefore,  while  it  is  suggested 
that  as  an  iodide  it  may  have  travelled  through  the  waterways  of  the 
Silurian  rocks,  it  is  not  meant  that  in  its  long  journeyings  before  it 
arrived  at  the  place  where  it  is  now  found,  it  did  not  pass  through 
many  changes  of  chemical  combination. 

The  precipitation  of  gold  from  solution  can  be  brought  about  in 
many  ways.  More  than  twenty-five  years  ago  certain  members  of 
the  Geological  Survey  of  Victoria  carried  out  a  series  of  experiments 

but  to  a  very  slight  degree  only.  Mr.  Eakins  is  still  prosecuting  this  series  of  in- 
teresting experiments. 

*  Judd's  Volcanoes,  p.  213. 

t  Palmieri's  Vesuvius,  p.  121. 


24      ORIGIN   OF   GOLD-BEARING   QUARTZ   OP   BENDIGO    REEFS. 

which  yet  remain  our  main  source  of  information  on  this  subject.  In 
1864,  an  accidental  discovery  by  Richard  Daintree  led  to  the  de- 
termination by  him  and  his  colleague,  Prof.  George  H.  F.  Ulrich,  of 
certain  conditions  under  which  the  precious  metal  is  deposited  from 
solution.*  It  was  demonstrated  subsequently  by  a  number  of  care- 
ful experiments  made  by  Wilkinson,f  that  organic  matter,  in  any  of 
the  ordinary  forms  in  which  it  is  found  to  occur  in  the  alluvial 
drifts,  is  readily  capable  of  precipitating  the  gold  of  even  the  weakest 
solutions,  and  of  depositing  it  as  a  thin  metallic  coating  upon  other 
particles  of  gold  or  upon  any  of  the  sulphide  minerals,  such  as  pyrite, 
galena,  or  blende,  with  which  its  occurrence  is  usually  associated. 

Several  years  later,  in  1871,  Daintree  was  in  London  and  at  Dr. 
Percy's  laboratory,  at  the  Royal  School  of  Mines,  commenced 
another  series  of  experiments.  In  different  bottles  he  placed  solu- 
tions of  chloride  of  gold  in  strong  solutions  of  chloride  of  sodium, 
containing  a  piece  of  pure  rock-salt,  and  to  each  he  added  a  crystal  of 
one  of  the  several  metallic  sulphides  commonly  found  in  gold-ores. 
Four  years  later,  and  before  any  results  had  been  obtained,  he  died. 
The  chemical  reactions  which  he  had  set  to  work  were,  however,  pro- 
ceeding slowly  but  surely.  I  now  quote,  Mr.  Richard  Pearce,  who 
was  an  eye-witness  of  both  the  beginning  and  the  consummation  of 
these  experiments. 

"  When  Daintree  died,  one  of  the  bottles,  namely,  that  containing  a  gold  solution 
and  a  crystal  of  common  pyrite,  was  removed  to  Dr.  Percy's  laboratory  in  Glouces- 
ter Crescent,  and  there,  in  1886,  the  work  which  Daintree  had  begun  came  to  frui- 
tion. On  the  smooth  surface  of  the  crystal  of  pyrite  there  had  been  deposited  a 
cluster  of  crystals  of  gold." 

*  The  following  interesting  account  of  what  has  become  an  historical  event  was 
given  to  me  by  my  distinguished  friend,  Prof.  Ulrich,  now  of  the  University  of 
Otago,  New  Zealand,  and  with  his  permission,  I  reproduce  it  here: 

"I  was  engaged  in  the  laboratory  analyzing  a  zeolitic  mineral,  whilst  Daintree 
himself  was  busy  with  some  photographs.  Suddenly  he  made  ejaculations  of  aston- 
ishment, and  on  my  asking  the  reason,  he  showed  me  a  small,  common  medicine- 
bottle,  which  contained  (more  than  half  full)  a  water-clear  fluid  in  which  floated 
a  part  of  the  cork.  The  cork  remaining  in  the  neck  of  the  bottle  was  acid-eaten. 
At  the  bottom  of  the  bottle  there  was  a  large  speck,  or  rather  little  nugget,  of  bright 
gold.  He  explained  that  he  had  made  a  concentrated  solution  of  chloride  of  gold 
for  the  purpose  of  toning  his  photographic  prints.  He  had  placed  in  it  a  small 
speck  of  gold.  *  And  now  see  (turning  the  bottle  upside  down), 'the  speck  has  grown 
to  such  a  size  that  it  won't  go  through  the  neck  of  the  bottle.'  We  both  agreed  that 
the  organic  matter  of  the  cork  had  been  the  cause  of  the  decomposition  of  the  solu- 
tion and  the  growth  of  the  gold." 

f  The  late  Mr.  Charles  Wilkinson,  Government  Geologist  of  New  South  Wales, 
at  that  time  junior  assistant  in  the  Geological  Survey  of  Victoria. 


ORIGIN    OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS.      25 

It  had  taken  fifteen  years  to  obtain  the  result,  and  the  man  who 
started  the  investigation  did  not  live  to  see  his  work  fulfilled  ;  but 
what,  it  may  well  be  asked,  is  the  brief  time  of  even  a  generation 
when  compared  to  those  vast  aeons  during  which  Nature,  in  her 
greater  laboratory,  is  carrying  out  operations  similar  to  these? 

It  is  interesting  to  be  able  to  add  as  a  sequel  to  the  above  that  in 
the  ore  of  the  St.  Louis  mine,  in  Gilpin  county,  Colorado,  crystals 
of  pyrite  have  been  found  which,  while  in  themselves  non-aurifer- 
ous, were  yet  dotted  over  with  clusters  of  crystalline  gold  remarka- 
bly similar  to  those  obtained  by  Daintree's  experiment* 

The  persulphate  of  iron,  which  is  also  a  vehicle  for  the  removal 
of  gold  from  one  place  to  another,  is  reduced  by  organic  matter, 
with  the  formation  of  gold-bearing  pyrite.  Under  like  conditions 
silicate  of  gold  solutions  would  precipitate  their  gold.  Again,  me- 
tallic sulphates  or  alkaline  sulphide  waters  containing  metallic  sul- 
phides in  solution  would,  on  meeting  alkaline  carbonates  in  the 
presence  of  organic  matter,  be  compelled,  by  reduction  and  neutrali- 
zation respectively,  to  form  a  deposit  of  metallic  sulphides,  f  Finally, 
iodide  solutions  are  readily  reduced  by  organic  matter  or  by  ferrous 
sulphate,  while  the  presence  of  both  together  would  lead  to  the 
formation  of  an  auriferous  pyrite. 

We  need  now  to  recall  the  fact  that  the  original  sediments  con- 
tained imbedded  with  them  numerous  remains  of  the  organic  life  of 
the  ancient  seas,  many  of  whose  forms  were  subsequently  preserved 
in  the  rocks  as  the  fossils  which  now  enable  us  to  determine  the 
stratigraphical  position  of  the  slates  and  sandstones.  Other  rem- 
nants of  the  more  minute  organisms  such  as  abounded  in  the  waters 
of  the  ocean,  though  they  left  behind  them  no  recognizable  forms, 
yet  were  doubtless  mixed  among  the  silt  and  mud  which  fell  to  the 
bottom  of  the  Silurian  seas.  Such  organic  matter  in  process  of  time 
became  decomposed  irito  its  constituent  elements,  those  which  were 
soluble  being  removed  by  underground  waters  while  the  insoluble 
remained  to  undergo  further  decomposition.  In  this  case,  as  often 
happens  in  the  laboratory  of  Nature,  the  solvent  and  the  precipitant 
formed  part  of  the  same  substance,  whose  disintegration  liberated 
the  one  from  the  other,  both,  however,  to  meet  again  and  to  react 
upon  each  other  at  a  later  period.  Thus  the  iodine,  which  is  a  sol- 
vent for  gold,  was  set  free  while  the  carbon,  which  is  a  precipitant, 

*  My  authority  is  again  Mr-  Richard  Pearce. 
f  Le  Conte's  Elements  of  Geology,  p.  245. 


26      ORIGIN   OF   GOLD-BEARING   QUARTZ   OF   BENDIGO   REEFS. 

remained  in  the  residue  and  became  converted  into  the  graphitic 
material  which  darkens  the  rock  encasing  the  quartz  lodes. 

This  graphitic  material  was  the  precipitant  for  the  gold  solutions. 
Its  occurrence  in  certain  lodes  has  been  pointed  out  by  others*  but 
its  very  frequent  association  with  gold  quartz  has  not  been  fairly 
recognized.  In  the  main  auriferous  belt  of  California,  passing 
through  the  counties  of  Amador,  Calaveras,  Tuolumne  and  Mari- 
posa,  an  encasing  formation  of  black  slate  is  known  by  experience 
to  be  a  favorable  indication,  while  a  gray  or  greenish-gray  country- 
rock  is  considered  less  encouraging.  At  Amador  City,  in  the  county 
of  the  same  name,  I  have  seen  men  coming  up  from  underground 
with  faces  and  hands  all  sooty  black  by  reason  of  contact  with  the 
graphitic  slate  which  there  and  elsewhere  in  that  region  encloses  the 
quartz  veins.  In  New  Zealand,  more  particularly  in  the  province 
of  Otago,  the  gold-bearing  lodes  are  similarly  characterized  by  a 
black  selvage,  the  somber  tint  of  which  is  due  to  carbonaceous  ma- 
terial. In  the  mining  districts  of  the  continent  of  Australia,  as 
well  as  in  the  gold-fields  of  the  island  of  Tasmania,  the  slates  and 
metamorphic  schists,  which  so  generally  form  the  prevailing  country- 
rock,  are  dark,  and  the  clay  which  lines  the  walls  of  the  reefs  is 
black  and  graphitic.  Such  is  the  case  also  in  the  mines  of  Bendigo. 
It  is  not,  therefore,  necessary  to  go  far  to  find  an  agent  capable  of 
precipitating  the  gold  from  its  state  of  solution  in  the  underground 
waters  of  the  rocks,  f 

That  gold  does  occur  in  solution  in  the  underground  waters  of  to- 
day has  been  shown  by  the  evaporation  of  large  quantities  of  ordt- 
nary  mine-water  and  the  finding  of  gold  in  the  residuum,^  also  by 
its  occurrence  in  the  incrustation  of  boilers  using  mine-water.§  It 
has  been  proved  By  the  examination  of  old  mine  timbers  left  in 
abandoned  workings  and  the  discovery  in  the  decayed  and  often 
silicified  'wood  of  crystals  of  pyrite  which 'were  distinctly  gold- 
bearing.  ||  Furthermore,  it  may  be  added  that  in  the  gravel  of  the 
deep  leads,  at  Ballarat,  for  example,  there  has  been  found  driftwood 


*  As,  for  instance,  by  Sandberger,  in  connection  with  the  veins  of  the  Erzge- 
birge. 

f  How  far  electro-chemical  and  electro-magnetic  forces  may  have  aided  these  re- 
actions cannot  be  estimated.  That  they  took  some  part  is  highly  probable. 

J  First  proved  by  Daintree. 

%  Also  by  Daintree,  at  the  mines  at  Maryborough. 

||  Notes  on  the  Physical  Geography,  Geology  and  Mineralogy  of  Victoria,  by  A.  K.  C. 
Selwyn  and  G.  H.  F.  Ulrich.  Melbourne,  1866. 


ORIGIN   OF   GOLD-BEARING  QUARTZ   OP   BENDIGO   REEFS.      27 

yielding  assays  of  from  a  few  pennyweights  to  several  ounces  of 
gold  per  ton.* 

The  occurrence  of  the  metallic  sulphides,  such  as  arsenical  and 
ordinary  iron  pyrites,  galena,  and  blende,  the  minerals  most  com- 
monly found  at  Bendigo  in  association  with  the  gold,  brings  up  a 
large  field  of  conjecture.  Sandbergerf  showed  that  iron,  zinc,  lead, 
copper  and  other  metals  occurring  in  lodes  can  also  be  found  in  cer- 
tain silicates  common  to  the  crystalline  rocks,  such  as  olivine,  augite, 
hornblende  and  mica.  His  deductions  have  not  been,  however,  en- 
tirely accepted.  At  Bendigo  the  lode-formation,  though  evidencing 
metamorphic  action,  is  yet  sedimentary.  It  may,  perhaps,  be  sug- 
gested that  the  granite  contributed  the  metallic  sulphides  associated 
with  the  gold  and  quartz,  but  there  is  no  evidence  to  support  such 
an  explanation.  While  the  frequency  of  the  occurrence  of  ore- 
deposits  in  association  with  eruptive  rocks  is  a  fact  now  widely  re- 
cognized, yet  it  has  given  rise  to  generalizations  not  altogether  war- 
ranted. In  this  particular  district  the  contact  is  not  a  place  of  ore- 
deposition,  and  the  main  series  of  producing  mines  is  seven  miles 
distant.  There  are,  it  is  true,  certain  anticlinal  formations  of  quartz 
not  far  from  the  granite ;  but  they  appear  to  have  no  relation  to  tl}e 
contact,  and  they  are  not  economically  of  any  importance.  The 
geological  evidence  of  the  region  has  suggested  that  the  granite  was 
a  factor  in  the  process  of  ore-deposition,  but  it  does  not  indicate 
that  this  rock  was  the  source  of  the  gold  or  of  the  associated  sul- 
phides. 

In  this  connection  I  would  hazard  the  remark  that  the  near 
neighborhood  of  igneous  rocks  is  favorable  to  the  occurrence  of  ore- 
bodies,  not  always  or  necessarily  because  such  rocks  were  the  origin 
of  the  precious  metals  which  were  leached  out  from  them,  but  often 
because  the  extrusion  of  such  eruptive  rocks  afforded  the  heat  and 
steam  which  gave  an  intensified  chemical  activity  to  percolating 
solutions. 

The  Silurian  sediments  were  obtained  from  the  erosion  of  pre- 
existing rocks,  whose  disintegrated  particles  probably  contained  the 
material  required  to  form  the  sulphide  minerals  of  the  reefs. 
Whether  the  metals  were  dissolved  in  the  waters  of  the  palaeozoic 

*  Investigated  by  the  above-mentioned,  and  also  by  J.  Cosmo  Newberry,  analyst 
to  the  Geol.  Survey  of  Victoria. 

f  Engineering  and  Mining  Journal,  March  22  and  29,  1884,  xxxvii.,  pp.  218 
and  232.  Translation  of  first  chapter  of  '*  Untersuchungen  iiber  Erzgiinge,"  by 
Fridolin  Sandberger.  Wiesbaden,  1882. 


28      ORIGIN   OP   GOLD-BEARING    QUARTZ   ON    BENDIGO    REEFS. 

seas  and  were  subsequently  chemically  precipitated,  or  whether  they 
were  deposited  by  mechanical  agency  among  the  silt  and  sand  which 
fell  to  the  ocean  bed,  is  a  question  not  now  to  be  determined. 

In  the  reefs  of  the  Bendigo  gold-field  the  metallic  sulphides  are 
present  in  an  unusually  small  proportion.  Iron  pyrites  is  much 
the  most  abundant.  A  great  deal  of  the  richest  ore  of  the  deepest 
workings  of  the  mines  is  a  clean  white  quartz,  almost  entirely  free 
from  any  accessory  minerals.  Such  quartz  frequently  contains  the 
gold  in  an  extremely  coarse  form,  in  pieces  weighing  many  penny- 
weights.* The  presence  of  pyrite  is  not  necessarily  an  evidence  of 
the  poverty  or  richness  of  the  quartz.  Rich  ore-bodies  often  con- 
tain a  good  deal  of  it,  just  as  poor  ones  sometimes  do.  Other  min- 
ing-districts afford  a  similar  experience.  We  must  recognize  that 
the  sulphates  of  iron  act  very  differently  with  an  increase  or  de- 
crease of  the  oxygen  they  carry.  Ferrous  sulphate,  FeO,  SO3,  is  a 
precipitantf  for  gold  solutions,  while  ferric  sulphate,  Fe2Os,  3  SO3,J  is 
a  solvent.  May  not  this  fact  help  to  explain  the  irregularity  of  the 
phenomena  attending  the  presence  of  pyrite  in  gold-ores  ? 

The  limitations  to  the  length  of  this  contribution  must  prevent 
the  discussion  of  theories  explanatory  of  the  process  by  which  the 
gold  and  quartz  were  actually  brought  to  the  place  where  we  now 
find  them.  Modern  teaching  and  experience  has  advanced  that 
theory  of  ore-deposition  which  has  been,  not  at  all  happily,  called 
t(  lateral  secretion."  It  is  to  the  effect  that  the  origin  of  the  pre- 
cious metals  as  found  in  lodes  is  to  be  ascribed  to  the  immediately 
encasing  rock,  out  of  which  they  have  been  leached  by  solutions, 
which  afterwards  by  endosmotic  flow,  penetrated  the  walls  of  the 
fissure  and  there  deposited  the  gold  and  silver.  Such  an  explanation 
is,  I  respectfully  submit,  more  in  harmony  with  the  teachings  of  a 
professor's  laboratory  than  with  the  testimony  of  underground  ob- 
servation. No  theory  so  narrow  as  that  framed  on  a  phenomenon 
as  specific  as  endosmosis  can  live  in  the  air  of  the  mines  where  the 
modes  of  occurrence  of  the  ore  have  an  infinitude  of  variety  which 
even  the  most  general  of  explanations  can  hardly  hope  to  cover. 
As  our  stock  of  ascertained  facts  slowly  accumulates,  as  each  dis- 

*  At  the  Lazarus  Mine,  at  a  depth  of  over  2000  feet,  I  saw  pieces  of  gold  ex- 
ceeding an  ounce  in  weight  in  a  large  reef  of  clean,  white,  splintery  quartz. 

f  It  is  the  precipitant  employed  in  the  chlorination-works  of  California  and  else- 
where. Charcoal  is  also  used  for  the  same  purpose. 

J  The  formula  is  not  rigid.  The  so-called  sesqui-sulphates  of  iron  are  of  vari- 
able composition. 


ORIGIN   OF   GOLD-BEARING    QUARTZ   ON   BENDIGO   REEFS.     29 

tant  mining  district  sends  in  its  quota  of  recorded  observations,  we 
shall,  I  believe,  find  that  "  lateral  secretion  "  in  its  narrowest  mean- 
ing is  rarely  tenable,  that  is,  that  while  the  material  of  ore-deposits 
may  have  been  and  probably  was  derived  from  the  leaching  of  the 
rocks,  it  did  not  necessarily  or  often  come  only  from  those  which  are 
immediately  adjacent  to  the  walls  of  the  lodes.  In  the  case  of  the 
Bendigo  "  saddles  "  we  are  led  to  believe  that  the  gold  and  the  quartz 
were  derived  from  the  mass  of  the  surrounding  formation  rather 
than  from  that  small  portion  only  which  immediately  adjoins  the 
reefs.  In  the  process  of  ore-deposition  and  lode -formation  this 
gold-field  was  a  part  of  a  greater  area,  in  which  similar  phenomena 
of  segregation*  took  place,  an  area  which  included  nearly  all  of  the 
numerous  and  productive  gold-mining  districts  of  the  colony  of 
Victoria.  Bendigo  was  especially  favored  because  of  the  very  pe- 
culiar structure  of  its  beds  of  slate  and  sandstone. 

It  may  be  objected  to  the  general  explanation  which  has  been 
offered  with  regard  to  the  origin  of  the  gold  and  the  quartz  that  if 
it  be  accepted  as  true,  all  sedimentary  rock  formations  should  be 
equally  capable  of  profitable  exploitation.  The  answer  is  obvious, 
namely,  that  to  the  miner  the  mere  dissemination  of  gold  in  rocks  is 
a  fact  economically  of  no  importance,  since  it  is  only  by  its  concen- 
tration in  certain  quantities  and  in  certain  forms  of  ore-deposit  that 
it  can  repay  him  for  the  toil  and  expense  of  its  extraction.  In  the 
Silurian  rocks  of  the  Bendigo  district  conditions  obtained  and 
agencies  were  at  work  which  were  particularly  effectual  in  collecting 
the  gold  from  its  wide  and  even  dissemination  to  its  concentration 
in  the  reefs. 

The  richness  of  the  gold-field  is  owing  primarily  to  two  causes, 
the  structure  of  the  country-rock  whose  extreme  and  very  regular 
folding  gave  rise  to  unusual  facilities  for  the  percolation  of  under- 
ground waters,  and  the  occurrence  in  the  slates  and  sandstones  of  a 
precipitant  able  to  compel  the  deposition  of  the  gold. 

It  is  a  striking  fact  that  while  the  anticlines  necessarily  alternate 
with  syncliues,  the  latter  are  not  the  places  of  ore-deposition.  "  In- 
verted saddles,"  as  the  miners  call  them,  do  indeed  occasionally 
occur;  but  they  are  not  economically  of  any  importance.  The  ex- 
planation is  a  simple  one.  By  the  mechanical  principle  of  the  arch 

the  anticlinal  structure  tends  to  preserve  a  passage  for  mineral  solu- 

» . . 

*  This  word  "  segregation  " — the  separating  out  of  material  and  its  regathering 
together  elsewhere — best  covers  the  process  of  lode-formation  in  this  particular 
region. 


30      ORIGIN   OF   GOLD-BEABING   QUARTZ   ON   BENDIGO   REEFS. 

FIG.  14. 


Drawing  of  Bendigo  made  in  1851. 


ORIGIN   OF   GOLD-BEARING   QUARTZ   ON    BBNDIGO    REEFS.      31 

tions,  while  on  the  contrary  the  basin  or  trough,  formed  by  the 
synclinal  arrangement  of  the  beds,  tends  by  the  action  of  gravity  to 
become  closed.  It  is  not  probable  that  the  apex  of  the  anticlines 
was  marked  by  an  open  way  ;  but  we  are  justified  in  supposing  that 
along  the  anticlinal  axes  there  were  portions  of  rock  more  loose  and 
more  permeable  than  the  country  surrounding  them.  These  we  may 
liken  to  arched  canals  through  whose  long  passages  mineral  solu- 
tions have  circulated  from  pre-Devonian  times  till  now,  bearing 
with  them  that  golden  freight  which  by  reason  of  the  reducing 
action  of  the  carbonaceous  matter  lining  their  walls  they  were  com- 
pelled little  by  little  to  lay  down. 

Thus  we  arrive  at  a  stage  when  from  wide  and  uniform  dissemina- 
tion through  enormous  rock-masses  the  gold  and  the  quartz  have 
become  concentrated  along  certain  lines  and  in  certain  localities,  but 
nature  is  never  at  rest;  they  are  no  sooner  laid  down  than  they  be- 
come again  wanderers  through  the  underground  waterways.  The 
causes  operating  to  remove  them  from  one  place  and  to  concentrate 
them  in  another  are  forever  at  work.  We  speak  of  secondary  deposi- 
tion in  cases  where  we  think  we  clearly  recognize  the  removal  of 
metallic  ore  from  one  place  to  another;  but  as  a  matter  of  fact  all 
the  ore-deposits  of  the  mines  are  concentrations,  and  in  their  nature 
secondary,  from  the  period  when  their  constituent  parts  formed  a 
portion,  relatively  large  or  infinitely  small,  of  the  first  sediments 
laid  down  upon  the  floor  of  the  ocean  to  that  time  long  afterward 
when  the  pick  of  the  miner  disturbs  that  which  for  ages  has  been 
going  through  a  process  of  continual  change  and  evolution. 

Thus  the  silica  which  as  fine  sand  fell  to  the  bed  of  the  sea,  in 
process  of  time  united  with  other  elements  and  became  a  part  of  a 
complex  mineral  which  we  call  a  silicate.  That  silicate,  by  the  rever- 
sal of  the  reactions  which  had  brought  it  into  existence,  became  subse- 
quently disintegrated,  the  silica  was  set  free,  and  as  quartz  later  on 
became  the  matrix  enclosing  the  gold.  From  that  state  of  admix- 
ture it  was  separated  by  the  contrivances  of  man  or  by  the  less  noisy 
and  more  powerful  agencies  of  heat  and  cold,  wind  and  rain,  to  be 
swept  into  the  running  stream  which  carried  it  into  the  waters  of 
the  ocean  in  whose  silent  depths  it  was  destined  again  to  "  sow  the 
dust  of  continents  to  be." 

Similarly  the  Silurian  slates  and  sandstones  may  have  been  them- 
selves derived  from  the  erosion  and  disintegration  of  the  granites, 
other  portions  of  which  afterwards  intruded  among  them.  Or, 
again,  there  is  reason  to  believe  that  the  granite  may  have  been 


32    ORIG.IN  OF  GOLD-BEARING  QUARTZ  ON  BENDIGO  REEFS. 

formed  by  the  extreme  metamorphism  of  the  lowermost  members  of 
the  Silurian  series.  Upbuilding  and  disintegration  in  the  mineral 
creation  like  life  and  death  in  the  organic  world,  are  but  correlative 
parts  of  one  continuous  process.  They  are  different  aspects  of  that 
indestructibility  of  matter  and  transmutation  of  energy  which  are 
taught  no  less  by  the  formation  of  a  quartz  reef  than  by  the  unfold- 
ing of  a  flower. 

At  that  point  in  the  long  sequence  which  marks  the  present  time,  the 
eye  lingers  on  rolling  woodland  and  winding  road,  grassy  meadows 
and  fleecy  flocks,  glancing  from  the  busy  activity  of  the  railway  to 
the  peaceful  quietness  of  the  farm,  to  be  finally  arrested  as  it  catches 
the  gleam  of  the  Bendigo  mines,  white  islands  in  the  dark  blue  sea 
of  the  lovely  Australian  bush,  that  vast  forest  of  Eucalyptus  whose 
leafy  waves  have  replaced  the  watery  wastes  of  palaeozoic  times. 


Fig.  14  is  a  reproduction  of  a  drawing  of  the  Bendigo  field  as  it 
appeared  in  1851.  The  upright  mass  of  quartz  in  the  foreground 
is  the  "  west  leg  "  of  a  saddle- formation,  while  just  beyond  the  two 
pools  of  water  (now  ornamental  lakes  in  the  grounds  of  Mr.  George 
Lansell's  residence)  there  is  seen  an  actual  saddle,  outcropping  at 
the  surface. 


/o 
Subject  to  Revision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


LA    GARDETTE:    THE  HISTORY  OF  A  FRENCH  GOLD 

MINE. 

BY  T.    A.    RICKARD,    ALLEMONT,    ISERE,   FRANCE. 

(Baltimore  Meeting,  February,  1892.) 

THE  mountains  of  the  picturesque  Dauphine,  in  southeastern 
France,  have  long  been  known  to  collectors  as  the  source  of  many 
minerals  of  rare  occurrence;  but  they  contain  also  several  mines, 
which,  though  less  known,  date  from  the  time  of  the  Saracens, 
many  centuries  back,  to  that  of  the  graduate  from  the  JScole  des 
Mines. 

In  the  department  of  the  Isere,  upon  the  cliffs  of  Villard  Ey- 
mond  and  overlooking  the  lovely  valley  of  the  Oisans,  is  the  his- 
toric gold-mine  of  France,  a  mine  interesting  as  much  for  its  record 
as  for  its  geological  features. 

The  gold-bearing  character  of  the  quartz  of  La  Gardette  was 
known  to  the  Greeks,  the  Romans,  and  later  to  the  Saracens,  all  of 
whom  at  various  periods  extracted  the  gold  of  the  outcrop  which 
ribs  the  mountain-side.  Mention  of  this  mine  is  found  in  certain 
rare  manuscripts  of  the  seventeenth  century,  but  it  was  in  1733  that 
the  first  serious  working  was  inaugurated.  In  that  year  the  ex- 
ploration of  the  vein  was  undertaken  by  order  of  the  king,  much 
to  the  disgust  of  the  inhabitants  of  Bourg  d'Oisans,  to  whom  it  has 
been,  both  in  earlier  and  later  times,  a  source  of  revenue,  either  di- 
rectly by  the  extraction  of  small  quantities  of  gold-ore  or  indirectly 
by  the  attraction  which  it  has  presented  to  passing  travellers.  The 
working  of  the  mine  by  the  State  had  no  results  of  importance  and 
shortly  ceased.  In  1765,  the  mine  was  again  given  over  to  the 
peasantry.  In  1776,  the  king' conceded  to  his  brother,  the  Comte 
de  Provence,  afterwards  Louis  XVIII.,  a  large  number  of  mines 
in  this  district.  La  Gardette  was  included ;  but  work  under 
this  grant  was  directed  to  the  mines  of  Les  Chalanches,  near 
Allemont,  in  the  neighboring  commune.  Here  a  foundry  was 
erected  under  the  supervision  of  M.  Binelli,  considered  one  of  the 
most  celebrated  mineralogists  of  his  time.  In  1781,  Binelli  was 
replaced  by  Schreiber,  a  Saxon  engineer,  -whose  name  is  interwoven 


2          LA   GARDETTE:    THE   HISTORY    OF   A    FRENCH   GOLD    MINE. 

with  that  of  nearly  all  the  old  mines  of  this  part  of  Europe.  At 
that  time  a  peasant  named  Laurent  Gardent  came  to  Allemont  to 
see  M.  Schreiber  and  to  show  him  certain  specimens  of  gold-quartz 
recently  extracted  from  the  lode  at  La  Gardette.  Schreiber  made 
an  examination,  was  much  impressed  with  what  he  saw,  and  forth- 
with started  for  Paris,  where,  upon  his  arrival,  it  was  decided  to 
commence  at  once  the  exploitation  of  the  mine.  Systematic  work- 
ing was  then  started  under  the  personal  supervision  of  the  best 
mining  engineers  of  that  period. 

This  discovery  of  a  gold-mine  is  said  to  have  produced  a  great  sen- 
sation  in  Paris.  All  the  literature  of  that  time  makes  mention  of 
the  matter,  and  the  arrival  in  1783  of  the  first  ingots  of  gold  aroused 
great  enthusiasm  at  the  Court. 

In  1786,  the  Comte  de  Provence  caused  a  medal  to  be  struck,  the 
gold  of  which  was  the  product  of  this  mine.  The  matter  was 
placed  in  the  hands  of  L?  Academic  des  Inscriptions  et  Belles  Lettres, 
which  chose  Dupre  to  execute  the  designs.  One  side  of  the  medal 
represented  Louis  XVI.,  and  the  other  the  Comte  de  Provence,  in 
the  act  of  offering  to  the  king  the  first  product  of  a  French  gold- 
mine. 

The  cost  of  this  medal  was  put  down  at  8000  livres,  and  it  has 
been  sarcastically  said  that  this  represented  all  the  results  thus  far 
obtained  by  the  enterprise.  It  certainly  marked  the  most  brilliant 
period  of  the  history  of  the  mine,  for  soon  after,  in  1788,  work  was 
discontinued.  It  is  reported  that  gold  was  found  chiefly  in  the 
upper  levels,  but  that  the  irregular  distribution  of  the  precious 
metal,  together  with  other  circumstances,  caused  the  abandonment 
of  active  exploitation.  Among  the  "other  circumstancts  "  it  is  safe 
to  include  the  insufficient  quantity  of  gold  in  the  ore;  for  in  those 
days,  as  now,  there  were  men  who  knew  how  to  avoid  laying  un- 
necessary stress  upon  this  somewhat  important  feature  of  gold- 
mining. 

After  1788,  followed  a  blank  period,  during  which  the  mine  was 
the  property  of  the  commune.  The  extraction  of  specimens,  both 
of  gold  and  of  rock-crystal,  was  actively  carried  on,  and  helped  to 
beautify  collections  in  many  of  the  less  distant  towns.  More  par- 
ticularly it  was  then  that  the  basis  was  laid  for  the  fine  collection  now 
to  be  seen  at  the  museum  in  Grenoble. 

Under  the  first  Empire  no  work  was  done  on  the  mine ;  but  the 
mining  engineer-in-chief  at  that  time,  Hericart  de  Thury,  was  in- 
structed to  write  a  report,  which  appeared  in  the  Journal  des  Mines, 


LA    GARDETTE:    THE    HISTORY    OF   A    FRENCH    GOLD   MINE.         3 

in  1806.  The  times  were  troubled,  and  the  complications  of  politics 
allowed  the  mine  to  remain  in  oblivion  until  1837,  when  a  fitful  re- 
opening took  place.  In  1839,  the  property  was  acquired  by  M.  Van 
de  Velde  for  a  Parisian  company,  which,  under  the  management  of 
M.  Graff,  caused  the  mine  to  be  re-opened  in  1841.  Some  very  rich 
pockets  of  specimen-gold  were  found,  but  no  serious  prospecting  was 
done,  and  no  important  results  were  obtained. 

The  mine  then  passed  through  the  hands  of  several  proprietors, 
under  whose  management  far  more  gold  was  expended  than  was  re- 
turned, and  more  than  was  returned  was  stolen. 

In  1862,  La  Gardette  came  into  the  possession  of  two  Englishmen, 
Messrs.  Fisher  and  Watson  ;  but,  upon  the  departure  of  the  latter 
for  the  more  productive  mines  of  Australia,  the  former  became  dis- 
couraged and  ceased  work.  Since  then  nothing  has  been  done  to 
forward  its  development,  save  the  writing  of  reports  by  the  suc- 
cessive mining  engineers-in-chief,  to  whom  it  seems  always  to  have 
furnished  the  subject  of  a  sort  of  graduation -essay. 

Recently  the  re-opening  of  La  Gardette  was  considered  by  the 
English  company  now  working  the  mines  at  Allemont ;  and  the 
writer  was  called  upon  to  examine  it.  The  results  of  that  examina- 
tion, as  stated  below,  bring  the  history  of  La  Gardette  up  to  date. 

The  history  of  the  mine,  as  outlined  above,  finds  a  ready  explana- 
tion in  the  study  of  the  conditions  under  which  the  gold  occurs.  An 
obtuse  disregard  of  the  facts  as  disclosed  in  the  workings  and  a  belief 
in  wild  theories  of  ore-deposition  have  been  the  causes  of  the  re- 
peated failures  to  make  it  profitable. 

The  gold  of  La  Gardette  occurs  in  a  quartz-vein  traversing  the 
gneiss,  which  in  this  district  has  a  great  variety  of  hardness  and 
composition.*  The  lode  is  of  extraordinary  regularity  in  strike, 
dip  and  parallelism  of  walls.  It  runs  nearly  due  east  and  west,f 
and  makes  an  angle  of  75°  with  the  horizon. 

The  gangue  is  almost  entirely  quartz,  with  a  highly  developed 
banded  or  ribbon-structure.  Slickensides  characterize  the  walls.  The 
minerals  accompanying  the  quartz  are  galena,  iron  and  copper 
pyrites  and  (rarely)  gray  copper.  It  has  been  noted  that  the  coarse 
galena  J  is  favorable  to  the  presence  of  gold.  The  richest  quartz 


*  The  French  engineers  variously  apply  to  it  the  terms  gneiss,  protogine  and 
crystalline  schists 

f  Or,  as  the  French  simply  put  it — "  vers  sept  d  huit  heures." 
J   "  A  grandes  facettes." 


4         LA   GARDETTE  :    THE   HISTORY   OF   A    FRENCH   GOLD   MINE. 

is  that  which  has   a  bluish-black    color,*  an    experience    in    har- 
mony with  that  of  other  gold  mining  districts. 

This  is  not  the  only  known  occurrence  of  gold  in  the  district, 
though  it  is  the  only  one  which  has  risen  to  the  dignity  of  a 
mine.  M.  de  Thury,  mining  engineer-in-chief  under  the  first  em- 
pire, has  left  the  record^  that  there  are  several  gold-deposits  in 
the  department  of  the  Is&re  : 

1.  At  Portraut,  at  the  foot  of  the  glaciers  of  the  Grandes  Rousses, 
where  it  occurs  in  association  with  argentiferous  lead  ore 

2.  At  Auris,  on  the  southern  slope  of  the  same  range,  and  nearly 
opposite  La  Gardette,  in  a  complex  lead-copper  ore,  associated  with 
antimony. 

3.  At  Mollard,  near  Allemont,  in   argentiferous  galena;  also  in 
the  copper  pyrites  of  La  Corchette  and  in  that  of  Les  Chalanches, 
Allemont. 

In  later  times  I  have  found  it  in  noteworthy  quantities  in  the 
quartz  of  the  Mine  des  Arabes,  at  Allemont,  where  it  is  associated 
with  galena,  blende  and  pyrites,  but  occurs  more  particularly  in 
thin  seams  of  maroon -colored  earth.  It  is  found  in  the  argentif- 
erous galena  of  Grand  Clos,  near  La  Grave,  as  well  as  in  certain 
quartz-veins  above  La  Yillette.  Nearly  all  the  ores  of  this  district 
which  I  have  had  cause  to  assay  have  shown  traces  of  gold. 

Returning  to  La  Gardette,  we  may  consider  briefly  the  geological 
conditions.  The  gneiss,  traversed  as  already  remarked  by  this  lode, 
is  overlain  by  the  dolomite  of  the  Trias  and  that  in  turn  by  the 
lime-sh:ile  of  the  Lias,  both  of  which  formations  have  been  identi- 
fied by  their  fossil  remains.  The  Trias  is  but  slightly  represented, 
and  here  varies  in  thickness  from  5  to  20  meters.  The  Lias  is  repre- 
sented by  lime-shale,  but  its  upper  horizon  is  diversified  by  the 
slate,  the  contorted  bedding  of  which  is  a  striking  feature  of  the 
cliffs  above  Bourg  d'Oisans.  In  it  occur  the  slate-quarries  of  Alle- 
mont and  Oz.  ... , 

The  vein  does  not  penetrate  the  overlying  secondary  formations, 
but  ceases  at  the  upper  eroded  edges  of  the  gneiss.  Where  the  vein 
ceases,  two  stringers  or  small  seams  of  quartz  extend  a  little  way  up 
into  the  Trias.  These  stringers  contain  galena  which  is  gold-bear- 
ing, also  copper  and  iron  pyrites;  in  fact,  they  have  much  the  same 
mineralization  as  the  main  lode  itself.  They  do  not  reach  the  Lias. 
The  accompanying  sketch  (Fig.  1)  illustrates  these  conditions. 

*  "Quartz  enfume,  tfun  bleu  noirdtrc."  f  Journal  des  Mines,   1806. 


LA    GARDETTE  :    THE   HISTORY   OF   A    FRENCH    GOLD   MIXE.          5 

The  Trias  is  a  metalliferous  horizon  containing  a  notable  pro- 
portion of  iron  pyrites,  usually  in  fine  grains,  arranged  in  small 
seams,  which  ramify  through  the  mass  of  the  formation. 

The  lode  of  La  Gardette  answers  to  the  term,  much  misused, 
and  often  but  little  understood,  "  true  fissure- vein."  In  this  in- 
stance we  have  a  "  gold-quartz-vein,"  and  it  is  necessary  to  recog- 
nize separately  each  one  of  the  words  which  make  up  the  name. 
In  practice  it  is  too  little  recognized  that  a  vein  may  (as  "true 
fissure-veins "  are  popularly  supposed  to  do)  continue  indefinitely 
downward  through  the  crust  of  the  earth,  but  unless  it  carries  gold- 
Fig,  i. 


CROSS-SECTION      SHOWING 
RELATIONS     OF     LA  GARDETTE     LODE. 


quartz  it  is  commercially  of  no  value,  however  interesting  scientifi- 
cally it  may  be.  Further,  the  gold-quartz  may  be  continuous,  but 
unless  the  precious  metal  is  present  in  a  certain  proportion  it  ceases 
to  be  valuable  to  the  miner.  Here  at  La  Gardette  we  have  a  very 
beautiful*  specimen  of  this  type  of  ore-deposit;  and  in  attempting 
to  arrive  at  its  probable  history  it  is  necessary  to  distinguish  between 
the  vein  and  the  lode,  between  the  fissure  and  the  mineral  matter 
deposited  in  or  along  that  fissure. 

It  is  evident  that  the  vein   is  anterior  to  the  deposition  of  the 

*  By  reason  of  its  striking  regularity  of  structure. 


6         LA   GARDETTE:    THE   HISTORY   OF   A    FRENCH   GOLD   MINE. 

Trias,  and  consequently  much  older  than  the  Lias.  The  two  vein- 
lets  which  start  from  the  upper  edge  of  the  vein  and  penetrate  the 
Trias  owe  their  origin  to  movements  which  caused  fractures  to  be 
formed  in  the  Trias,  and  at  this  point  are  in  line  with  the  course  of 
the  main  fissure,  because  the  latter  was  a  line  of  least  resistance. 

The  fact  that  the  mineralization  of  the  veinlets  in  the  Trias  is 
identical  with  that  of  the  upper  part  of  the  main  lode  in  the  gneiss 
points  to  a  common  origin.  It  appears  to  me,  therefore,  that  while 
the  formation  of  the  fissure  of  La  Gardette,  as  well  as  the  deposi- 
tion of  the  quartz  of  the  lode,  antedated  the  laying  down  of  the 
beds  of  the  Trias,  it  was,  notwithstanding,  from  the  overlying  Trias 
that  the  lode,  in  common  with  these  veinlets,  may  have  derived  a 
certain  portion  of  its  metalliferous  contents. 

When  the  gneiss  was  eroded  during  the  period  preceding  the 
deposition  of  the  Trias,  the  lode-cropping  was  also  denuded,  with 
a  resulting  natural  concentration  along  the  apex  of  the  vein.  In 
later  times,  after  the  Trias  period,  further  mineralization  took  place 
to  an  extent  not  now  ascertainable.  The  practical  result  was  that 
that  portion  of  the  lode  which  was  immediately  under  the  Trias  was 
enriched,  and  that  this  part  of  the  vein  became  really  the  only  com- 
mercially valuable  part  of  it. 

Upon  the  fact  just  stated  hinges  the  whole  history  of  the  mine. 
The  gold  first  discovered  was  in  the  capping  immediately  under  the 
dolomite  cliffs  of  the  Trias,  where  the  original  cap  of  the  lode  had 
been  laid  bare,  as  in  the  times  before  it  was  covered  by  the  sedi- 
ments of  the  Triassic  seas.  This  part  of  the  mine  was  very  rich  in 
pockets  of  free  gold,  and  soon  became  exhausted.  Afterwards,  when 
capital  had  been  obtained,  the  engineers  who  had  charge  of  the 
spending  of  it  directed  their  attention  to  the  deeper  parts;  their  con- 
fidence of  increased  richness  with  depth  augmenting  in  proportion 
as  they  recognized  that  the  upper  parts  of  the  mine  were  becoming 
exhausted.* 

Successive  administrations  essayed  and  failed  to  open  up  a  pro- 
ductive mine  at  lower  levels ;  while,  during  the  intervals,  the  peasants 
scratched  about  in  the  upper  workings  and  found  occasional  speci- 
mens. 

To-day  the  history  of  the  development  of  the  mine  can  be  read  in 
the  underground  workings.  Owing  to  the  comparative  smallness 

*  Many  of  the  reports  of  the  French  engineers  declare  that  increasing  richness 
may  be  expected  with  increasing  depth.  This  is  a  fallacy  too  frequently  repeated 
in  later  times  by  men  who  have  seen  far  more  of  gold-mining. 


LA    GAKDETTE  :    THE    HISTORY   OF   A    FRENCH    GOLD    MINE.         7 

of  the  lode,  its  great  regularity  and  the  hardness  of  the  enclosing 
rock,  the  workings  are  all  readily  accessible.  The  upper  develop- 
ment consists  of  adits  alone ;  the  lower,  of  shafts  connecting  a  series 
of  levels.  The  total  vertical  depth  explored  exceeds  400  feet.  It 
is  seen  that  while  all  the  quartz  has  been  stoped  away  from  the  first 
level  up  to  the  sloping  floor  of  the  gneiss-dolomite  contact  above, 
and  a  winze  follows  that  contact  for  a  short  distance  under  the 
level,*  in  the  lower  workings,  on  the  other  hand,  hundreds  of  feet 
of  drifts  have  been  extended  without  the  stoping  of  a  fathom  of 
ground.  In  the  uppermost  part  of  the  lode  the  quartz  is  bluish  and 
ribboned,  containing  galena  and  pyrites ;  but  lower  down,  while  it 
still  carries  occasional  patches  of  pyrites,  it  is  white  and  barren.  The 
upper  portions  of  the  lode  have  a  width  of  20  to  25  centimeters,  but 
in  the  lower  levels  this  is  increased  to  30  and  40;  above,  it  is  com- 
pact ;  below,  it  is  full  of  geodes  lined  with  crystals.  While  the  upper 
part  has  been  a  gold-mine,  the  lower  part  has  been,  and  is  still  to-day, 
valuablef  for  rock-crystals  alone.  Assays  made  by  me  of  the 
quartz  standing  in  the  lower  level  gave  traces  of  gold  only. 

The  vein  is  remarkable  for  the  extreme  development  of  two 
features  common  to  many  gold  mines — slickensides  and  ribbon- 
structure. 

The  slickensidesj  extend  continuously  over  large  portions  of  the 
surface  of  the  wells,  for  a  length  of  400  meters  and  a  height  of 
over  80.  The  striae  are  nearly  horizontal,  an  evidence  of  a  very 
£i*eat  change  of  position,  indicating  a  movement  through  a  large 
angle.  That  this  is  not  impossible,  or  indeed  improbable,  is 
shown  by  the  evidence  of  similar  movements  to  be  found  in  the 
vicinity ;  at  Allemont,  for  instance.  This  change  of  position  was 
probably  contemporaneous  with  the  period  of  the  contortion  of  the 
schists  (or  gneiss);  and  both  were  in  all  likelihood  due  to  the  up- 
lifting action  of  the  granite,  a  boss  of  which  peeps  from  under  the 
limestones  of  the  Grandes  Rousses. 

The  very  beautiful  lamination  or  ribbon-structure  which  charac- 
terizes the  vein  has  received  frequent  mention  from  visitors.  M. 
Charles  Levy  records  that  in  one  band  alone,  9  centimeters  thick, 


*  This  has  much  to  remind  one  of  the  "contact "  and  "  verticals  "  in  which  the 
ore  occurs  at  Rico,  Colorado. 

f  M.  Napoleon  Albertas,  who  kindly  guided  me  over  the  mine,  exploits  the  lower 
workings  for  the  rock-crystals  found  there,  and'has  lately  shipped  groups  to  Paris 
which  brought  him  600  to  1000  francs  per  lot. 

bv  the  French  and  "harnische"  bv  the  Saxons. 


8         LA    GARDETTE:    THE   HISTORY   OF   A    FRENCH    GOLD   MINE. 

he  counted  38  laminae  or  ribbons.  To  some  of  those  who  have  de- 
scribed the  mine,  it  has  suggested  successive  reopenings  and  fillings 
by  crystallization.  To  others,  it  has  indicated  merely  intermittent 
crystallization. 

This  structure  of  gold-quartz- veins,  frequently  observed  in 
widely  separated  mining  districts,  is  generally  recognized  by  miners 
as  a  favorable  indication.  Allied  to  it  is  the  observation  that  milk- 
white  quartz  is  usually  less  likely  to  be  gold-bearing  than  that 
which  has  a  dark  or  bluish  tinge. 

The  explanation  of  the  ribbon-structure  does  not  require  the 
fanciful  imaginings  of  the  "successive  reopening  and  refilling''7 
theory.  That  the  lode  is  usually  an  altered  form  of  the  country 
which  the  gold-vein  traverses,  is  a  fact  now  generally  recognized. 
All  underground  observation  leads  one  to  look  upon  the  dark, 
nearly  parallel  lines  which  cause  the  ribboning  as  the  last  remnants 
of  included  fragments  of  country-rock.  In  the  gold-mines  of  Cali- 
fornia and  Australia,  one  can  frequently  note  the  transition  from  the 
large,  irregular  pieces  broken  from  the  lode-walls  to  the  small,  more 
regularly  arranged  fragments  which  serve  to  subdivide  the  width  of 
a  lode.  In  certain  cases  one  may  follow  the  slow  gradation  from 
quartz  filled  with  portions  of  "country"  to  dark  quartz  in  which 
the  traces  of  included  country  are  entirely  unrecognizable.*  At  La 
Gardette  it  is  to  be  noted  (the  fact  is  recorded  by  M.  Graff)  that 
when  the  vein  includes  fragments  of  the  inclosing  country,  such  in- 
clusions are  always  smaller  than  the  width  of  the  particular  band  of 
quartz  in  which  they  are  arranged. 

It  is  not  possible  to  imagine  that,  under  ordinary  circumstances,  a 
cavity  could  long  remain  empty  under  the  weight  of  the  overlying 
rocks.  Any  fracture  or  fissure  formed  must  immediately  tend  to 
close  up,  and  where  it  is  a  line  of  movement,  a  fault,  as  many  veins 
are,  the  effect  would  be  to  choke  it  up  with  fragments  torn  from  that 
wall  which  was  of  inferior  hardness.  Later  movements  along  the 
same  line  would  tend  to  shear  off  additional  portions  of  the  enclos- 
ing country.  Further,  it  has  been  shown  (by  Becker  at  the  Corn- 
stock,  for  instance),  that  the  action  of  a  fault  is  to  cause  a  sheeting 
of  the  country  by  fractures  in  sympathy  with  the  main  line  of 
fault.  This  structural  effect  might  also  come  into  play  within  a  lode ; 
for,  as  the  mineral  solutions  percolating  along  the  main  fissure  or 

*  In  Australia  this  would  be   the  transition  from  "rnullocky"  to  "  mottled 
quartz. 


LA   GARDETTE:    THE    HISTORY   OF   A    FHEXCH   GOLD    MINE.          9 

line  of  fracture  dissolved  portions  of  the  included  broken  country 
and  in  turn  deposited  quartz  or  other  lode-filling,  they  would  also 
follow  the  other  lines  of  fracture  lying  latent  in  the  adjoining  coun- 
try. The  result  would  be  one  of  those  cases  where  one  or  more 
" false  walls"  are  found,  and  where  it  is  only  the  proportion  of  gold 
present  which  determines  where  the  lode  may  be  practically  con- 
sidered to  cease.* 

In  thus  insensibly  passing  from  a  discussion  of  ribbon-structure 
to  that  of  lode-walls  I  have  but  followed  the  transition  which  occurs 
underground.  But  to  return:  When  the  lode  filling  is  less  hard 
than  the  enclosing  country,  there  is  always  a  likelihood  of  its  be- 
coming the  line  of  movements  similar  to  those  which  brought  it 
into  existence.  Later  faulting  would  take  place  along  the  lines  of 
included  country  rather  than  along  that  of  the  hard  quartz,  and 
would  result  in  the  crushing  of  those  portions  of  included  country 
and  their  arrangement  along  parallel  lines.  Occasionally  the  in- 
cluded country  is  harder  than  the  portions  of  the  vein  more  or  less 
incompletely  filled  with  quartz,  and  then  we  get  the  crushed  sugar- 
like  quartz  which  characterizes  several  well-known  lodes. 

Experience  shows  that  ribbon-structure  is  a  desirable  feature  of  a 
gold-vein.  In  the  mines  of  California  and  Australia  these  black 
lines  of  lamination  greatly  facilitate  the  actual  breaking  of  the 
quartz ;  but  besides  this  they  are  generally  found  to  characterize 
gold-bearing  rock.  This  fact,  common  to  districts  otherwise  very 
dissimilar,  is  something  more  than  a  coincidence.  These  black  lines 
are  often  graphitic,  f  the  evidence  left  by  metamorphism  of  the  or- 
ganic remains  deposited  in  the  original  sedimentary  rocks.  Such 
carbonaceous  matter  would  act  as  a  reducing  agent  upon  mineral 
solutions,  leading  to  the  precipitation,  for  instance,  of  gold  from  a 
chloride  solution.  In  some  of  the  mines  of  Victoria,  the  thin,  black 
seams  of  slate  dividing  the  quartz  are  found  to  be  covered  with  a 
mosaic  of  fine  gold.  In  California  similar  instances  are  not  un- 
known. 

In  this  connection,  one  is  reminded  of  the  fact  that  dark  and 
bluish  quartz  are  found  by  experience  more  likely  to  be  gold-bearing 
than  white  quartz.  There  is  a  distinction  to  be  made,  however,  be- 

*  It  is  a  bad  tendency  which  some  miners  have,  to  seek  for  "  walls,"  and  then, 
having  found  one,  to  desist  from  any  further  cross-cutting  through  the  lode. 

f  The  miners  of  Amador  county,  California,  when  they  come  up  from  under- 
ground, look  like  coal  miners,  on  account  of  the  black  slate  having  discolored  their 
clothes. 


10      LA    GARDETTE:    THE    HISTORY    OF   A    FRENCH    GOLD    MINE. 

tvveen  the  dark  and  the  bluish-tinted  varieties;  for  while  the  former 
appearance  is  probably  due  to  the  presence  of  minute  fragments  of 
black  slate  or  other  country-rock,  now  almost  entirely  replaced  by 
quartz,  the  latter  is  due  to  the  presence  of  sulphate  of  iron,  which 
may  be  either  original  or  a  secondary  result  of  the  decomposition 
of  iron  pyrites.  Such  quartz  becomes  rusty  by  oxidation  within 
the  zone  of  surface-decomposition.  In  this  case,  ferrous  sulphate 
may  play  the  part  of  the  graphitic  matter  of  the  black  slate. 

In  leaving  the  subject  it  is  well  to  add  that,  in  mining,  generali- 
zations are  always  dangerous  if  followed  too  far.  An  instance  is 
suggested  by  the  above  paragraph.  White  or  dull  whitish  quartz  is 
invariably  considered  by  the  California  miner  an  evidence  of  the 
poverty  of  the  vein ;  and  yet  I  have  seen  at  Bendigo  quartz  of  this 
character,  at  a  depth  of  over  2000  feet,  which  carried  gold  freely,  not 
in  an  isolated  pocket,  but  as  characterizing  a  lode-formation  over  a 
great  distance. 


NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors, 
or  communications  for  publication  as  "  Discussion,"  or  independent 
papers  on  the  same  or  a  related  subject,  are  earnestly  invited. 


Subject  to  Pevision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 

THE  MINES  OF  THE  CHALANCHE8,  FEANCE. 

BY  T.  A.  RICKARD,  DENVER,  COLORADO. 

(Bridgeport  Meeting,  October,  1894.) 

IN  southeastern  France,  among  the  magnificent  alpine  masses  of 
the  Dauphine",  there  is  a  group  of  celebrated  mines  of  silver-, 
nickel-  and  cobalt- ores,  the  deposits  of  which  present  many  features 
of  interest.  In  1891  I  directed  the  work  done  at  the  Chalanches, 
and  at  that  time  made  the  notes  upon  which  the  present  paper  is 
based. 

The  workings  consist  of  a  complex  series  of  adit-levels  entering 
the  heart  of  a  mountain,  the  summit  of  which  is  one  of  the  lower 
peaks  of  the  Belledonne,  in  the  commune  of  Allemont,  and  over- 
looking the  valley  of  the  Romanche  and  its  tributary,  the  Eau 
d'Olle.  The  lower  adits  are  3700  feet  above  the  village  of  Alle- 
mont, or  7250  feet  above  sea-level. 

HISTORICAL. 

The  discovery  of  these,  as  of  many  other  notable  mines,  was  acci- 
dental. In  1767,  JVIarie  Payen,  a  shepherdess  (bergere)  of  Alle- 
mont, found  an  outcrop  of  silver-ore,  and  brought  away,  in  ignorant 
curiosity,  a  lump  of  heavy  stone,  which  she  handed  to  the  village 
smith.  When  tested  on  his  forge,  the  molten  silver  trickled  from 
it.  The  shepherdess  received  600  francs  upon  her  wedding-day  as 
a  reward  for  the  discovery.*  Thereupon  some  of  the  peasants  of  the 
commune  began  to  dig  and  to  smelt  the  silver-chloride  ores,  the 
croppings  of  which  they  traced  down  the  mountain-side.  The  ex- 
ploitation thus  inaugurated  continued  with  but  little  interruption 
for  more  than  a  century. 

The  first  mining  done  was  digging,  f  A  loss  of  life  through  a 
crush  in  the  excavations  caused  the  authorities  at  Grenoble  to  take 

*  There  is  an  entry  on  the  pay-sheet  for  September,  1768,  made  in  the  hand- 
writing of  M.  Schreiber.  *'  Paid  to  bergere  Marie  Payen,  at  her  marriage  with  Jean 
Roux,  master  charcoal-burner  at  ihefonderie  d' Allemont,  the  sum  of  600  livres  as 
recompense  for  discovery  of  the  mine." 

f  '*  Gophering  "  or  "  coyoting." 


2  THE   MINES   OF   THE   CHALANCHES,    FRANCE. 

official  cognizance  of  these  operations ;  and  M.  Lemonnier,  a  mem- 
ber of  the  Academy  of  Sciences,  was  sent  by  order  of  the  king  to 
investigate  the  discoveries  of  silver  reported  to  have  been  made  by 
the  peasants. 

In  1769,  systematic  work  was  commenced  under  the  direction  of 
a  Piedmontese  engineer,  M.  Binelli.* 

On  the  10th  of  June,  1776,  the  king  granted  a  concession  of  these 
mines,  as  well  as  those  of  Allemont  and  La  Gardette,f  to  his  brother, 
the  Comte  de  Provence,  afterwards  Louis  XVIII.  Smelting-fur- 
naces  were  erected  at  the  base  of  the  mountain  near  Allemont. 

In  1781,  Binelli  gave  place  to  Schreiber,  who  assumed  the  direc- 
tion of  the  smelting  establishment  and  of  the  various  mines.  Sehrei- 
ber's  name  is  interwoven  with  the  history  of  most  of  the  mines  in 
this  part  of  Europe.  He  was  a  Saxon  engineer  of  much  ability,  and 
was  the  father  of  the  ficole  des  Mines,  which  was  first  established  at 
Moutiers  in  Savoy. 

On  the  2d  of  August,  1792,  as  a  consequence  of  the  Revolution, 
the  mines  became  national,  and  passed  into  the  hands  of  the  new 
government. 

The  >ears  intervening  between  1776  and  1791  cover  the  most 
prosperous  period  in  the  history  of  the  mines.  In  1791,  the  amount 
of  development- work  was  decreased,  and  the  profits  dwindled  away 
under  bad  administration.  The  silver  produced  was  sent  away,  but 
the  amount  of  money  necessary  to  pay  for  the  work  was  not  for- 
warded to  the  mines.  Accounts  were  liquidated  with  billets  or 
promissory  notes  instead  of  cash.  Matters  went  slowly  from  bad  to 
worse  until  1807,  when  the  State  abandoned  operations  and  made  a 
concession  of  the  mines  to  a  public  company. 

From  the  first  discovery  up  to  1801,  a  period  of  thirty-two  years, 
the  mines  produced  9453  kilos,  or  303,514  Troy  ounces  of  silver. 
According  to  Schreiber,  the  receipts  were  2,098,421  francs,  or  65,577 
francs  per  annum.  The  expenses,  1,890,056  francs,  equal  to  59,090 
francs  per  annum.  During  this  period  there  were  times  when  the 
lodes  became  very  much  impoverished,  and  the  profits  were  further 
diminished  by  the  erection  of  reduction- works,  buildings  and  other 
outlays.  There  remained,  nevertheless,  a  net  balance  of  207,585 


*  For  many  of  these  data  I  am  indebted  to  an  Extrait  des  Memoires  de  la  Societe 
des  Ingenieurs  Civils  by  M.  Alfred  Caillaux. 

f  See  "La  Gardette :  The  History  of  a  French  Gold-Mine,"  by  the  writer. 
Trans.,  vol.  xxi.,  p.  79. 


THE    MINES   OF   THE   CHALANCHES,    FRANCE. 

francs.  The  best  years  were  1784  and  1785,  when  the  profits 
amounted  to  55,000  and  54,000  francs  respectively. 

In  1808,  Schreiber  became  director  of  the  jficole  des  Mines  at 
Moutiers,*  and  ceased  to  manage  the  Chalanches.  In  1809,  a  new 
company  obtained  control  of  the  mines  through  an  imperial  decree. 
It  was  short-lived,  and  was  succeeded  by  a  series  of  other  compa- 
nies, which  did  more  or  less  work  iu  an  unsystematic  manner  up 
to  1873.  In  1889,  application  was  made  by  Pierre  Manin  for  a 
concession  of  the  then  abandoned  mines,  A  company,  La  Societe 
Savoy  sienne,^  was  formed  to  operate  mines  in  Savoy  and  in  the 
Dauphine,  including  those  of  the  Chalanches.  This  ambitious  enter- 
prise exhausted  its  energy  in  making  large  promises,  and,  after  a  brief 
existence,  was  sold  out  for  the  benefit  of  its  creditors.  The  Countess 
de  Grail ly  became  proprietress  of  the  Chalanches,  and  of  Grand 
Clos,  the  mines  of  which  have  always  been  worked  in  conjunction 
with  the  former. 

In  1890  the  mines  passed  into  the  hands  of  an  English  Company, 
the  "  French  Mines,  Ltd.,"  and  vigorous  work  was  commenced  at 
the  Chalanches,  as  well  as  at  Les  Arabes,  Villaret  and  Grand  Clos. 
Owing  to  the  fact  that  the  other  mines  of  this  extensive  group 
offered  better  inducements  for  the  investment  of  capital  in  their  de- 
velopment, the  Chalanches  was  operated  to  a  limited  extent  only. 
The  exploratory  work  led  to  the  discovery  of  several  rich  pockets  of 
silver-ore  and  small  patches  of  nickel-  and  cobalt-ores.  On  the 
whole,  however,  the  results  were  not  such  as  to  encourage  further 
work,  and  in  September,  1891,  operations  ceased.  These  interesting 
old  mines  are  therefore  again  abandoned. 

Resume  of  the  History  of  the  Mines. — The  record  of  the  Chalan- 
ches presents  a  story  similar  to  that  which  is  told  of  mines  in  more 
modern  mining  districts.  The  inaccessibility  of  the  mines  in  winter, 
the  richness  of  the  ore,  its  great  fusibility  and  the  consequent  sys- 
tematic robbery  of  the  silver  are  local  commonplaces.  Circumstan- 
ces all  worked  together  to  make  the  Chalanches  mines  the  prey  of 
the  most  barefaced  plunder.  With  the  aid  of  a  common  forge-fire, 
even  without  the  intervention  of  a  crucible,  and  with  little  knowl- 

*  Sometimes  spoken  of  as  the  "  Ecole  des  Mines  de  Pesey."  The  mines  of  Pesey 
and  Macot,  in  the  hills  of  old  Savoy,  were  the  cause  of  the  choice  of  Moutiers,  the 
nearest  town,  as  the  locality  for  the  first  school  of  mines. 

f  That  Gallic  imagination  by  no  means  falls  short  of  the  Anglo-Saxon  faculty 
when  it  is  applied  to  prospectus-making,  is  proved  by  the  flamboyant  style  in 
which  the  promoters  of  the^oci&e  Savoysienne  addressed  the  public. 


4  THE   MINES   OF   THE    CHALANCHES,    FRANCE. 

edge  or  skill,  lumps  of  silver  could  be  produced  from  the  very  rich 
chlorides,  ruby  silver  and  black  sulphides  which  constituted  in  the 
main  the  soft  earthy  ores  or  terres  found  in  the  crevices  of  the  out- 
crop. Aged  inhabitants  still  talk  sportively  of  the  theft  like  old 
smugglers,  and  point  out  nooks  in  the  woods  which  the  remaining 
ruins  of  the  little  furnaces  dug  out  by  the  miners,  show  to  have  been 
the  scenes  of  former  illicit  silver-ore  smelting.  In  these  furnaces, 
no  larger  than  an  ordinary  fire-place,  dug  in  the  earth  and  smeared 
with  clay,  with  charcoal,  or,  failing  that,  clods  of  dung  for  fuel,  and 
two  or  three  little  urchins  to  blow,  like  cherubs  on  the  old  maps, 
out  trickled  the  white  metal.  Clergy  and  people  joined  cheerfully 
in  these  moonlighting  operations  without  in  any  degree  shocking 
local  ethics.  The  priest  at  Allemont,  who  lately  restored  the  parish 
church,  says  that  the  old  church  had  a  room  adjoining  the  sacristry, 
in  which  a  former  reverend  father  used  to  melt  down  the  silver-ore 
brought  to  him  by  the  faithful.  The  slags  were  concealed  in  an  ex- 
cavation under  the  floor,  where  a  large  accumulation  of  them  was 
found  when  the  church  was  restored. 

During  the  earliest  period  of  mining  at  the  Chalanches,  some 
bodies  of  extremely  rich  ore  were  found  near  the  surface.  It  is 
said*  that  two  shots  produced  sufficient  silver  to  pay  for  the  two 
buildings  known  as  the  pavilions  at  Allemont,  with  their  various 
ornamentations,  including  the  fleurs-de-lis  which  still  adorn  the  roof. 
As  200  to  300  kilos  of  silver  would  at  that  time  be  worth  from 
$10,000  to  $15,000,  this  statement  does  not  seem  incredible,  f 

A  "  pockety  "  mine  is  notoriously  apt  to  be  loosely  and  extrava- 
gantly managed.  The  uncertainty  of  the  work  is  prejudicial  to  the 
maintenance  of  system.  The  various  companies  that  operated  these 
mines  from  1808  to  1873,  did  so  at  a  loss,  due  largely  to  inexperi- 
enced engineering  and  loose  financial  management. 

M.  Geymard,  an  engineer  of  repute,  says  of  this  interval  of  sixty- 
five  years : 

"Explored,  exploited,  abandoned  and  resumed  by  new  companies,  the  mine  paid 
dividends  or  levied  assessments  according  to  the  ability  of  the  men  sent  to  take  charge 

*  For  this  information,  and  many  notes,  I  am  indebted  to  my  father,  Mr.  Thomas 
Rickard. 

f  An  idea  of  the  value  of  the  ore,  outside  the  patches  of  extremely  rich  mate- 
tial,  may  be  gathered  from  a  statement  made  by  M.  Schreiber,  in  a  report  sent  to 
the  Academic  and  afterwards  reproduced  in  the  Annales  des  Mines,  that  the  average 
richness  of  the  Chalanches  ore  treated  in  the  furnaces  at  Allemont,  up  to  that  time, 
was  750  grammes  per  100  kilos,  equivalent  to  about  219  Troy  ounces  per  ton  of 
2000  pounds  avoirdupois. 


THE    MINES   OF   THE   CHALANCHES,    FRANCE.  5 

of  the  works  and  according  to  the  amount  of  the  capital  placed  at  their  disposal. 
To  sum  up,  the  mining  was  restricted  to  the  workings  opened  up  by  Schreiber ;  for 
all  his  successors  confined  themselves  to  a  few  meters  of  development  and  explora- 
tion among  the  old  drifts." 

M.  Caillaux,  summarizing  the  history  of  this  period,  adds : 

"  The  mines  of  the  Chalanches  were  never  worked  on  a  proper  scale  during  the 
present  century  and,  as  has  been  well  expressed  by  M.  Gruner,  the  want  of  success 
marking  the  various  attempts  made  during  this  lapse  of  time  does  not  in  any  way 
prove  the  sterility  of  the  ore-deposits,  or  the  impossibility  of  its  being  operated  to 
advantage." 

The  latter  part  of  this  statement  is  open  to  discussion. 

It  is  not  a  little  remarkable  that  although  the  silver  is  always 
associated  in  the  lodes  with  rich  nickel-  and  cobalt-ores,  often  with 
bunches  of  stibnite,  and  more  rarely  and  erratically  with  gold,  the 
government  engineers  took  no  note  of  any  metal  other  than  silver. 
None  of  the  valuable  metals  mentioned  figure  in  the  old  accounts. 
The  speiss  containing  nickel  and  cobalt  was  rejected  with  the  slags, 
and  went  to  fill  the  swamps  and  to  form  the  road-beds  which,  in 
later  times,  were  furrowed  and  turned  over  to  recover  their  valuable 
contents.* 

The  possibility  of  utilizing  three  metals  instead  of  one  seems  to 

*  It  has  not  been  found  possible  to  ascertain  the  value  of  the  old  mattes  with 
which  roads  were  made  and  marshes  filled,  but  the  following  notes  will  assist : 
Herr  O.  F.  Kotttg,  writing  from  Oberschlema,  August  7,  1889,  with  regard  to  the 
speiss,  picked  up  in  the  old  smelter-dump  and  shipped  by  Pierre  Manin,  says  that 
it  contained  3.6  per  cent,  metallic  cobalt,  8.9  per  cent,  metallic  nickel,  and  0.2  per 
cent,  silver.  Another  lot  gave  3  Co,  11.8  Ni,  and  0.3  Ag.  This  speiss  was  neglected 
during  Schreiber's  time. 

In  August,  1863,  the  Viscount  de  Talon  sent  7  barrels  of  ore  to  Vivian  &  Sons, 
Swansea.  The  ore  in  these  barrels  ranged  in  value  (net)  from  £3  to  £31  per  ton, 
not  including  the  silver.  The  average  was  about  £16.  The  nickel  was  valued  at 
Is.  9c?.  per  pound,  the  cobalt  at  7s.  per  pound.  The  smelting  charge  was  £1.10.0 
per  ton.  The  contents  of  the  barrels  were : 

No. 

1,  .  .  . 

2,.  .  . 

2,.  .  . 

3,.  .  . 

4,.  .  . 
5,  . 

5,  .  .  , 

6,  .  -.  ;     . 
7,.  .  . 


Nickel. 

Cobalt. 

Silver. 

Cwt. 

Qr. 

Lbs. 

Per  cent. 

Per  cent. 

Oz.  per  ton. 

16 

0 

9 

.6 

.07 

11 

2 

0 

6 

2.6 

1.30 

47 

3 

0 

6 

1.1 

0.60 

19 

6 

0 

10 

3.2 

2.00 

81 

17 

3 

26 

3.0 

1.60 

201 

1 

0 

8 

2.3 

1.6 

86 

3 

0 

7 

3.8 

1.9 

192 

23 

3 

9 

3.2 

1.9 

27 

1 

1 

8 

4.3 

3.3 

39 

6  THE  MINES  OF  THE  CHALANCHES,  FRANCE. 

have  dawned  upon  the  later  engineers  quite  as  a  discovery ;  and  this 
fact  stimulated  the  repeated  spasmodic  attempts  to  rehabilitate 
the  old  mine.  The  arsenides  of  nickel  and  cobalt  were  sold  in 
England  and  in  Germany.*  More  recently,  a  German  chemist  was 
employed  at  Allernont  in  an  experiment  to  manufacture  cobalt 
pigments  for  the  arts.  He  was  not  successful,  and  the  attempt 
was  abandoned. 

In  1891  the  gold-value  was  first  recognized. f  Its  importance 
proved  greater  from  a  scientific  than  from  a  commercial  point  of 
view.  The  old  mine- workings,  aggregating  20  kilometers  in  length, 
showed  that  a  great  deal  of  unsuccessful  exploration  had  been  car- 
ried out.  Search  among  these  galleries,  particularly  near  the  sur- 
face, resulted  in  the  finding  of  certain  rich  bunches  of  ore,  which 
were  soon  exhausted.  An  attempt  to  introduce  the  tribute-  or  lease- 
system  was  made,  with  partial  success.  The  necessity  for  concen- 
trating the  operations  of  the  company  led  to  more  active  work  at 
Grand  Clos  and  Les  Arabes,  and,  at  the  same  time,  made  it  advisable 
to  abandon  the  Chalanches. 

THE  ORE-DEPOSITS. 

The  geological  formation  is  simple.  A  network  of  veins  traverses 
crystalline  schists  of  very  variable  character.  The  country  forms  a 
part  of  the  great  crystalline  formation  usually  referred  to  as  the 
Archaic  schists  of  the  Alps,  though  in  point  of  fact  they  probably 
include  rocks  from  the  granite  up  to  the  Carboniferous.  Lithologi- 
cally,  certain  sections  suggest  the  Huronian  and  Laurentian.  These 
schists  lie  immediately  upon  the  granite;  they  are  extremely  varia- 
ble in  character,  so  that  at  different  places  they  can  be  described  as 

*  The  Chalanches  mines  were  always  worked  in  conjunction  with  those  of  Grand 
Clos,  near  La  Grave.  The  lead-ores  of  the  latter  were  brought  about  20  miles  to 
Allemont,  to  be  smelted  with  the  products  of  the  Chalanches.  The  smelting 
was  simple.  The  lead-sulphides  and  the  arsenides  of  nickel  and  cobalt  were 
submitted  to  stall-roasting,  and  then  passed  through  a  low  blast-furnace  (four  d 
manche),  giving  as  products:  (a)  work-lead,  containing  the  silver,  and,  of  course, 
the  gold,  if  present;  (6)  speiss,  containing  the  nickel  and  cobalt;  (c)  slags.  The 
work-lead  went  in  succession  to  Pattinsonage  and  cupellation  for  the  extraction  of 
the  silver.  The  speiss  and  slag  went  over  the  dump.  It  was  only  in  later  years 
that  the  nickel  and  cobalt  were  taken  account  of. 

f  Small  samples  of  the  earthy  ore  gave  occasionally  as  much  as  1  to  1^  ounces 
per  ton.  At  Les  Arabes,  a  mine  just  above  the  village  of  Allemont,  there  occurred 
narrow  streaks  of  maroon -colored  earthy  stuff,  which  assayed  from  2  to  as  high  as 

7  ounces  of  gold  per  ton. 


THE   MINES    OF   THE   CHALANCHES,    FRANCE.  7 

gneissose,  granitoid,  talcose,  micaceous,  graphitic,  or  amphibolic.* 
At  the  base  of  the  slope  leading  to  the  mines  there  are  superb  blocks 
of  rock,  containing  crystalline  epidote. 

Chalanches,  like  the  mines  of  the  Alps  generally,  in  France,  in 
Savoy,  or  in  Switzerland,  is  far  up  toward  the  summit  of  the  com- 
plicated schist-region.  Looking  across  the  valley  of  the  lovely 
Romanche,  one  can  see  La  Gardette,  the  historic  gold-mine  of 
France,  perched  upon  the  cliffs  overlooking  Bourg  d'Oisans.  Across 
the  winding  Eau  d'Olle  rises  the  imposing  mass  of  mountains  known 
as  "les  Grandes  Rousses."f  One  can  distinguish  their  structure, 
which  more  immediate  examination  proves  to  be  that  of  crystalline 
schist  overlain  patch-wise  by  the  dolomite  of  the  Trias,  in  turn 
succeeded  by  the  shales  and  slates  of  the  Lias. 

Immediately  above  the  Chalanches  mines  and  in  rocks  of  Car- 
boniferous age  there  is  a  deposit  of  anthracite.  To  the  anthracite 
succeeds,  in  fragmentary  deposits,  the  dolomite  limestone,  which, 
though  less  constant  than  the  Carboniferous  sandstone  and  shale, 
almost  always  accompanies  the  anthracite  basins,  and  in  the  Hautes 
AlpesJ  is  associated  with  what  appears  to  be  Permian  sandstone 
and  the  gris  bigarre.§  The  latter  fact  gives  rise  to  the  suggestion 
that  the  dolomite  belongs  rather  to  the  Permian  than  to  the  Trias. 

The  country  which  more  immediately  holds  the  lode-channel  of 
the  Chalanches  mines,  and  which  I  may  term  the  encasing  rock,  has 
the  character  of  gneiss.  In  actual  contact  with  the  veins  it  is  amphi- 
bolic and  contains  a  notable  amount  of  pyrite.  This  last  character- 
istic causes  it  to  emit  sparks  when  struck  with  steel  and  indicates  the 
origin  of  its  local  name,  la  roche  martiale. 

The  oxidation  of  the  pyrite  is  the  reason  of  the  red  bands  which 
seam  the  steep  bluff  crowning  the  upper  precipitous  summit  of  the 
mountain.  These  bands  of  pyritic  schist  dip  into  the  hill  just  as 
the  main  series  of  veins  does,  a  fact  which  led  M.  Graff,  a  distin- 

*  On  the  government  map  the  whole  mass  of  the  Chalanches,  as  also  the  Cor- 
neillion,  on  the  opposite  side  of  the  river,  is  marked  "  amphibolites."  Above  and 
beyond  Chalanches,  there  is  shown  a  peak  of  "  euphotide  amphibolique,"  flanked 
by  serpentine.  There  is  no  doubt  that  these  rocks,  on  either  side  of  the  Romanche, 
are  in  places  highly  amphibolic,  but  it  is  an  error  to  describe  the  entire  mass  ot 
the  mountain  as  such. 

f  I.e.,  the  great  "  roughs,"  ruffians,  or  rugged  ones. 

£  At  Argentiere  and  Valgaudemar. 

$  The  gres  bigai-re  is  the  Bunter  sandstone  of  the  Vosges,  where  it  rests  com- 
formably  on  the  red  Permian  sandstone.  (See  Geikie's  Textbook  of  Geology,  3d  ed., 
p.  870.) 


8  THE   MINES   OF   THE   CHALANCHES,   FRANCE. 

guished  engineer,  to  conclude  that  they  played  the  part  attributed 
to  the  fahlbands  of  Kongsberg,  in  Norway. 

The  maps  of  the  mine  exhibit  a  wonderful  network  of  galleries, 
spreading  like  a  cobweb  over  an  area  of  about  600  by  300  meters. 

It  is  computed  that  the  workings  aggregate  in  length  not  less  than 
12  miles,  an  extent  in  remarkable  contrast  to  the  relatively  small 
quantity  of  ore  produced. 

The  principal  veins  are  six  in  number,  four  of  which,  the  Cobalt, 
Prince,  Simeon  and  Hercule,  lying  about  15  meters  apart,  dip  rather 
flatly  into  the  mountain,  in  conformity  with  the  bedding  of  the  en- 
closing rock-formation,  while  the  two  others,  the  Directoire,  a  nearly 


Fig.  I. 


Cross-Section,  Showing  the  Veins  of  the  Chalanches. 

vertical  vein,  and  the  St.  Louis,  which  cuts  it  diagonally,  may  be 
considered  as  cross- veins  or  counter-lodes  to  the  main-series.  The 
accompanying  cross-section  (Fig.  1)  will  explain  these  relations. 

In  addition  to  the  six  lodes  mentioned  there  are  several  minor 
veins  which  may  be  considered  as  branches  or  feeders  of  the  main 
series,  the  whole  forming  a  complicated  web  of  ore-bearing  fissures, 
Schreiber  is  quoted  as  having  said  that  "  the  veins  have  as  many 
directions  as  there  are  points  of  the  compass."  Gruner  speaks  of 
Chalanches  as  "  a  mountain  radiated  and  fractured  in  every  direc- 


FRANCE.  9 

tion,  the  largest  fissures  being  filled  with  fragments  of  the  encasing 
rock  and  the  smaller  fissures  with  metalliferous  ores  of  very  varied 
character. "  Geymard  considered  the  lode-structure  to  be  a  stockwerk; 
but  Graff  distinguished  two  principal  groups  of  veins,  namely  (1) 
those  which  have  a  north-south  strike  and  dipped  either  east  or  west, 
apparently  parallel  to  the  lamination  of  the  encasing  schist,  and  (2) 
those  which  strike  east-west  and  dip  uniformly  to  the  north.  Ac- 
cording to  the  same  authority,  the  veins  north-south  were  the  most 
regular  and  continuous.  Both  series,  however,  were  stated  to  throw 
off  numerous  branches  and  thus  gave  rise  to  an  apparently  inex- 
tricable confusion. 

Of  the  engineers  quoted,  Graff  was  the  most  trustworthy  observer. 
His  description  of  the  veins  is  good.  Others,  even  Schreiber,  seem 
to  have  entirely  failed  in  mastering  the  difficulties  of  the  deposit. 
In  the  more  fissured  ground  near  the  surface  the  lode-formation  may 
bear  the  description  of  a  stockwerk,  or,  more  properly,  little  sep- 
arated patches  of  stockwerk;  but  in  depth  this  character  is  not  ap- 
parent. Observation  at  every  point  at  which  the  numerous  veins 
occur  along  the  southeastern  flanks  of  the  Belledonne  massif  goes  to 
prove  that  by  far  the  greater  number  of  the  veins  which  have  been 
mined  conform  to  the  bedding  and,  therefore,  dip  into  the  hill,  as 
the  Chalanches  lodes  do.  They  follow  the  flexures  and  folds  of  the 
schist,  and  naturally  present  all  kinds  of  variations  of  direction 
when  exposed  in  the  mine  workings.  This  is  also  observable  at 
Les  Arabes,  Villaret  and  Oulles.  The  cross-lodes  appear  to  be  rela- 
tively unproductive,  the  St.  Louis  and  Directoire  being  exceptions. 
It  may  be  said,  speaking  generally,  that  these  bedded  veins  in  the 
Dauphine*  are  weak,  inconstant  and  difficult  to  follow. f  They  are 
frequently  altogether  obliterated,  leaving  to  the  miner  the  bedding 
of  the  country  as  his  only  guide.  Hence  the  apparent  extravagance 
of  drifts. 

Towards  the  center  of  the  mine  workings  of  the  Chalanches  there 
are  three  dikes  of  diabase,  respectively  23,  3  and  30  meters  in  thick- 
ness. Furthermore,  all  those  who  have  at  various  periods  directed 
the  mines  take  note  of  large  barren  fissures  which  traverse  the 
mountain  and  dislocate  the  ore-bearing  veins.  They  are  filled  with 
fragments  of  country  and  with  clay,  both  sandy  and  micaceous. 
Schreiber  considered  them  as  barren  lodes  and  termed  them  " filons 

*  The  more  modern  departments  of  the  Isere  and  Hautes  Alpes. 
t  These  bedded  veins  in  the  schists  remind  one  often  of  the  lodes  in  the  quartzose 
schists  of  Otago.     (See  Trans.,  xxi.,  411  et  seq.) 


10  THE   MINES   OF   THE   CHALANCHES,    FRANCE. 

aauvages  priv'es  de  substances  m'etalliques"  A  Cornish  man  would 
call  them  "flookan." 

It  has  been  thought  by  several  observers  that  the  lodes  were  more 
numerous  near  the  surface  than  in  the  interior  of  the  mine.  This  is 
due  to  the  fact  that  any  single  fissure,  in  approaching  the  surface, 
spreads  itself  out  into  a  number  of  subordinate  fractures.  It  has 
also  appeared  that  the  lodes  gained  in  regularity  as  they  penetrated 
the  mountain.  Caillaux  therefore  adds  that  this  fact  seems  to  indi- 
cate the  probable  occurrence  in  depth  of  only  a  small  number  of 
lodes,  but  that  those  surviving  will  have  a  regularity  greater  than 
those  which  have  been  hitherto  exploited.  Regularity  of  structure 
would  be  a  poor  compensation  to  the  miner  for  the  fact  that  the  en- 
closing rock  is  much  harder,  and  the  thickness  of  ore  smaller,  than 
in  the  ground  nearer  to  daylight. 

The  veins  vary  in  width  from  a  knife-blade  to  80  centimeters  (31.5 
inches);  their  usual  thickness  lies  between  3  and  30  centimeters 
(0.1  to  1  foot).  The  following  data  from  my  note-book  will  indi- 
cate, in  a  general  way,  the  size  and  nature  of  the  veins : 

July  14,  1891. 

Premiere  Hercule. — 12  cm.  in  two  parts:  the  upper,  quartz  and 
fine-grained  galena ;  the  lower,  efflorescence  of  nickel 
(annabergite)  in  earthy  ore. 

Troisieme  Hercule. — 30  cm.  Antimonial  ore  (stibnite  and  ox- 
ide) accompanied  by  cobalt-bloom  (erythrine). 

Cinquieme  Hercule. — Vein  crossed  by  cross-course.  Broken  ; 
barren. 

St.  Nicholas. — 35  cm.  Brown  earthy  ore,  containing  arsenates 
of  nickel  and  cobalt,  with  native  silver. 

Galerie  d'  Argent. — 5  to  7  cm.     Wire  silver,  with   black  sul- 
phides of  silver,  in  an  earthy  gangue. 
August  11,  1891. 

Premiere  Hercule. — 10  cm.  Chiefly  calcite,  a  few  spots  of  ga- 
lena. 

Troisieme  Hercule. — 35  cm.     Calcite,  with  .threads  of  galena. 

Prince. — 20  cm.  Red  and  black  earthy  ore  (found  afterwards 
to  contain  35  ozs.  Ag)  stained  with  copper. 

Oinquieme  Hercule. — 7  to  10  cm.  Calcspar,  with  splashes  of 
stibnite. 

St.  Nicholas. — 12  cm.  Black  earthy  ore,  with  stones  of  fahlerz 
and  kupfernickel. 

Galerie  d' Argent. — 5  cm.    Black  earthy  ore,  full  of  native  silver. 


THE   MINES   OF   THE   CHALANCHES,    FRANCE.  11 

General  Conclusions  Regarding  the  Ore- Occurrence. — Some  of  the 
conclusions  of  several  accomplished  French  engineers  have  been 
quoted.  They  differ  according  to  the  condition  of  the  mine  at  vari- 
ous periods,  depending  upon  whether  the  development- work  was 
being  vigorously  pushed  ahead,  new  ground  opened  up  and  rich  ore 
extracted,  or  whether  the  work  of  exploration  was  restricted  and  the 
operations  confined  to  the  search  for  the  pockets  of  silver  which  were 
found  from  time  to  time  i'rregularly  distributed  amid  the  complex  of 
veins.  At  the  time  when  I  directed  the  work,  attention  was  mainly 
confined  to  the  exploration  of  blocks  of  ground  not  previously  inter- 
sected by  drifts  or  cross-cuts.  No  work  was  done  in  the  ends  of 
galleries  farthest  advanced  into  the  mountain.  My  experience  of 
the  mine  and  its  ore-deposits  led  me  to  the  following  conclusions : 

The  formation  of  crystalline  schists  has  been  subjected  to  fissuring 
at  more  than  one  epoch,  an  earlier  one  being  marked  by  the  fractures 
filled  with  ore  and  now  forming  the  lodes,  and  a  later  one  charac- 
terized by  the  formation  of  cross-fractures  which  broke  across  the 
previously  formed  lodes,  and  are  themselves  non-metal-bearing. 

Near  the  surface  the  lodes  are  soft,  especially  where  they  are 
richest  in  silver.  Though  they  agree  in  the  main  as  to  their  mineral 
impregnation,  the  daily  advance  of  drifts  will  exhibit  an  extraordi- 
nary variety  of  vein-filling.  They  all  contain  nickel,  cobalt,  silver, 
and  in  places  also  antimony  and  gold,  as  their  commercially  valu- 
able elements.  With  these  are  associated  the  numerous  mineral 
species  for  which  the  mines  are  famous,  notably  acicular  crystals  of 
epidote.  The  minerals  of  the  Chalanches  are  to  be  found  in  most 
of  the  important  collections  of  Europe.* 

Examination  of  the  old  workings  proves  clearly  that  with  increas- 
ing distance  from  the  surface  the  country  gets  harder,  the  veinstuff 
loses  its  soft  character,  the  veins  become  fewer  in  number,  more  reg- 
ular, less  wide  and  less  ore-bearing.  Approaching  the  surface,  on 
the  contrary,  the  schists  are  fractured  in  a  multiplicity  of  directions, 
the  veins  become  larger,  their  filling  is  generally  earthy,  and  they 
throw  off  branches,  at  the  intersections  of  which  ore-bodies  are  found. 
In  general,  mineralization  becomes  more  pronounced  with  approach 
to  daylight;  this  being  due,  not  merely  to  the  oxidation  of  the  sul- 
phides, but  to  an  actual  relative  increase  of  "  orey  "  matter. 

The  outer  portion  of  the  mountain  is  jointed  and  otherwise  frac- 

*  Its  contribution  to  the  Museum  of  Natural  History  at  Grenoble  would  itself  re- 
pay a  %Toyage  across  the  Atlantic.  All  the  mines  of  Leadville,  for  instance,  would 
hardly  furnish  a  richer  collection  of  minerals  than  the  Chalanches  alone. 


12 


THE   MINES   OF   THE   CHALANCHES,    FRANCE. 


tured  to  a  very  remarkable  degree.  The  seams  of  ore  which  follow 
such  joints  and  fractures  are  often  composed  of  earths  rich  in  nickel 
and  cobalt,  or  of  wire-silver  mud.  An  illustration  of  such  an  occur- 
rence is  afforded  by  the  pocket  of  native  silver  found  within  a  few 


Fig.  2. 


Fig.  3. 


Native  Silver 


Lamination  of  the  Schists 


Joints 


Sections  Showing  Pocket  of  Native  Silver. 

feet  of  the  surface,  at  the  intersection  of  the  St.  Louis  and  Cobalt 
veins,  in  July,  1891.  The  accompanying  sketches,  Figs.  2  and  3, 
show  the  change  in  the  lode-structure  as  the  working  progressed,  the 
time  between  the  two  drawings  being  four  days.  In  Fig.  2  the 
native  silver,  enclosed  in  a  black  mud,  and  accompanied  by  ochreous 


THE   MINES   OF   THE    CHALANCHES,    FRANCE.  13 

earth,  extends  from  one  vein,  across  the  point  of  intersection,  into 
the  other.  In  Fig.  3  the  silver  is  confined  to  the  upper  part  of  the 
Cobalt  vein.  Red  iron-earth  formed  the  filling  of  the  St.  Louis. 
The  structure  of  the  enclosing  country  is  merely  suggested  in  the 
drawings. 

The  observations  made  from  day  to  day  led  me  to  conclude  that 
the  richest  part  of  the  mine  was  that  which  was  within  the  influence 
of  oxidation,  and  that  both  chemical  agencies  and  structural  condi- 
tions favored  an  enrichment  of  ore  near  the  surface.  This  statement 
is  particularly  applicable  to  the  silver  contents.  It  also  holds  true 
of  the  gold,  but  it  is  less  accurate  with  respect  to  the  nickel  and  co- 
balt. The  richness  in  silver  of  the  oxidized  ores  suggests  secondary 
precipitation.  This  is  confirmed  by  the  fact  that  the  silver  appears 
to  be  thrown  down  upon  the  nickel  and  cobalt  arsenides,  and  often 
envelopes  them  in  such  a  way  as  to  impart  to  them  the  rudiments 
of  a  nodular  structure.  The  hard,  undecomposed  arsenides  con- 
tain only  small  amounts  of  silver.  The  gold,  only  occasionally 
present,  is  associated  invariably  with  soft,  maroon-colored,  earthy, 
iron-bearing  vein-stuff.  The  nickel  and  cobalt  minerals  appear  to 
be  primary  ores,  and  are  more  persistent  than  those  of  silver  and 
gold. 

The  dependence  of  the  occurrence  of  large  amounts  of  rich  ore 
upon  the  broken  and  fractured  character  of  the  country  would  seem 
to  me  to  indicate  that  that  particular  concentration  of  metallic  min- 
erals which  renders  the  deposit  economically  important  is  of  com- 
paratively recent  geological  date ;  for,  only  near  the  surface  (the  sur- 
face of  any  given  time,  not  necessarily  only  that  of  to-day)  were 
there  the  conditions  favoring  such  a  concentration.  A  study  of  the 
vein-structure  of  the  surrounding  region  shows  that  the  ore-bearing 
veins  are  younger  than  the  Jurassic  age.  This,  of  course,  applies 
only  to  the  fissures  in  which  the  ore  is  now  found.  The  actual  de- 
position of  ore  could  not  have  commenced  before  the  fracture  took 
place,  but  it  has  probably  been  going  on  ever  since.  At  the  Cha- 
lanches,  the  change  in  the  nature  of  the  ore- deposits,  both  in  struc- 
ture and  in  mineral  contents,  is  measured,  not  from  any  imaginary 
nearly  horizontal  surface  of  a  former  unknown  epoch,  but  from  the 
steep  slope  of  the  hillside  of  to-day. 

The  occurrence  of  deposits  of  nickel-ores  in  close  association  with 
basic  eruptives,  and  more  particularly  magnesian  rocks,  has  been 
frequently  noted.  The  country-rock  of  the  Chalanches  lodes  con- 
sists of  the  crystalline  magnesian  schistose  rocks,  which  have  been 


14        THE  MINES  OF  THE  CHALANCHES,  FRANCE. 

already  mentioned.  They  are  overlain  by  doloraitic  limestone,  and 
are  intruded  upon  by  a  mass  of  altered  gabbro  or  euphotide,  which 
is,  in  turn,  flanked  by  serpentine.  The  serpentine  may  have  been 
derived  by  the  metamorphism  of  amphibolic  schists,  euphotide,  or 
limestone.*  That  the  origin  of  nickel-deposits  is  traceable  to  the 
leaching  of  basic  eruptives ;  that  the  metal  and  its  ores  occur  in 
a  finely  disseminated  condition  in  such  rocks,  and  have  been  by 
them  brought  within  the  reach  of  circulating  waters,  is,  at  present, 
a  strongly  favored  theory. f 

As  bearing  on  this  part  of  the  subject,  the  following  additional 
facts  are  pertinent.  At  the  Chalanches,  in  addition  to  the  magne- 
sian  silicate  schists,  forming  the  encasing  rock  of  the  lodes,  there 
are,  at  least,  three  dikes  of  diabase.  Above  Bourg  d'Oisans  — six 
miles  distant — there  is  an  amygdaloidal  paelaphyre  (the  spilite  of  the 
French  geologists),  which  carries  nodules  of  calcite  accompanied  by 
sulphide  of  nickel. J  Between  Allemont  and  Vizille  there  are,  ac- 
cording to  the  government  map,  several  outcrops  of  spilite.  They 
are  usually  associated  with  the  upper  Trias,  and  occasionally  appear 
to  belong  to  the  Jurassic.  Certain  of  the  ore- bearing  veins  of  the 
district  penetrate  from  the  crystalline  schists  into  the  anthracite 
beds,  and  even  into  the  Lias,  the  last  being  the  youngest  formation 
of  the  lode-mining  portion  of  the  region. 

The  roche  martiale,  or  pyrites-bearing  bands  of  schist,  which  im- 
mediately contain  the  most  productive  veins,  illustrate  that  associa- 
tion of  nickel  and  iron  pyrites  which  has  been  often  remarked  by 
geologists. 

The  origin  of  the  metals  which  enrich  the  veins  of  the  Chalan- 
ches is  a  matter  which,  owing  to  the  limited  data  bearing  upon  it, 
cannot  be  discussed  at  great  length  with  profit.  The  silver  and 
gold  may  be  supposed  to  have  been  derived,  as  elsewhere,  from  as- 
cending solutions  which,  in  approaching  the  surface  deposited  their 
precious  contents  according  as  the  structural  conditions  of  the  rock 
or  the  chemical  composition  of  the  casing  of  the  fissures  may  have 
regulated  that  deposition.  The  nickel  and  cobalt  will  be  considered, 

*  That  serpentine  can  be  derived  by  metaraorphism  from  magnesian  silicate 
rocks,  or  from  limestone,  has  often  been  pointed  out — quite  recently  by  Mr.  S.  F. 
Emmons,  in  "Geological  Distribution  of  the  Useful  Metals,"  Trans.,  xxii.,  71. 

f  It  is  advocated,  for  instance,  by  Mr.  P.  Argall,  in  a  contribution  to  the  Colo- 
rado Scientific  Society,  entitled,  "  Nickel :  the  Occurrence,  Geological  Distribution, 
and  Genesis  of  its  Ore-Deposits." 

J  A  similar  occurrence  is  that  of  millerite,  or  sulphide  of  nickel,  recently  noted 
by  me  in  certain  hornblende-schists  at  the  Gipsey  Queen  Mine,  3|  miles  east  of 
Salida,  Colo. 


THE   MINES   OF   THE   CHALANCHES,   FRANCE.  15 

by  many,  to  have  had  a  more  definite  and  immediate  origin  in  the  mag- 
nesiau  silicates  of  the  diabase  and  schists,  out  of  which  they  will  be 
supposed  to  have  been  leached.  These  explanations  of  the  origin  of 
the  four  metals  mentioned  would,  in  that  case,  be  a  compromise  be- 
tween the  contending  views  of  the  two  sides  in  the  controversy 
between  the  extremes  of  lateral  secretion  and  ascension. 

It  will  be  claimed,  however,  that,  if  the  nickel  and  cobalt  were 
obtained  fiom  out  of  the  encasing  (the  wall-rock),  or  the  enclos- 
ing (the  remoter  country)  rock,  then,  there  should  be  some  differ- 
ence in  the  schists  penetrated  by  those  parts  of  the  lodes  carry- 
ing a  notable  amount  of  nickel  and  cobalt,  as  compared  to  the 
schists  in  which  the  lodes  are  barren.  It  cannot  be  said  that 
this  is  the  case.  The  bands  of  pyritic  schist  are  parallel  to  the 
lodes,  and  enclose  both  their  rich  and  their  barren  portions.  That 
the  lode-channel  is  marked  by  the  presence  of  schist  rich  in  pyrite 
is  true ;  but  the  fact  points  not  to  the  pyrite  as  the  source  of  the 
metal,  but  simply  to  a  probable  identity  of  source,  and  contempo- 
raneity of  deposition.  Within  the  reach  of  oxidizing  agencies,  both 
the  nickel  and  cobalt  arsenides  and  the  iron  pyrite  are  found 
decomposed  in  some  places,  unaltered  in  others.  The  interior  work- 
ings of  the  mine  show  veins  carrying  hard  unoxidized  ores  encased  in 
harder  schists,  the  pyrite  of  which  is  unaltered.  While  the  rock 
which  has  been  most  affected  by  oxidation  contains  veins  richer  in 
silver  and  gold  than  that  which  does  not  show  the  action  of  such 
agencies,  there  is  no  noteworthy  difference  in  the  nickel-  and  cobalt- 
contents. 

In  these  mines,  as  in  others  in  widely  separated  regions,  I  have 
observed  that  it  often  happens  that  a  very  narrow  but  very  rich 
streak  of  ore  may  occur  encased  in  hard  undecomposed  country, 
while,  on  the  contrary,  a  large  width  of  poor  veinstuff  may  be  en- 
closed by  highly  altered  and  mineralized  rock.  This,  which  is,  I 
believe,  a  common  observation  to  those  who  spend  much  time  under- 
ground, is  a  fact  forever  opposed  to  the  narrower*  views  of  any 
lateral-secretion  theory.  In  such  cases  it  is  evident  that  the  encas- 
ing rock  has  been  mineralized  and  enriched  through  the  agency  of 
solutions  which  travelled  in  the  lode-channel;  that  the  mineraliza- 
tion took  place  from  the  lodes  to  the  country  and  not  from  the  out- 
side country  toward  the  interior  of  the  lode-channel. f 

If  we  accept  the  current  theory  that  the  nickel  and  cobalt  came 

*  As  distinguished  from  the  wider  interpretation  given  to  that  theory,  not  by 
Prof.  Sandberger,  but  by  Mr.  Emmons  and  others  in  this  country. 

f  This  view  was  advocated  by  Mr.  Pearce  thirty  years  ago.  (See  Trans,  xxii.,  740. ) 


16  THE   MINES    OF   THE   CHALANCHES,    FRANCE. 

from  the  leaching  of  magnesian  silicates  (and  facts  are  numerous 
pointing  that  way),  then,  we  must  conclude  that  the  origin  of  the 
nickel  and  cobalt  of  the  Chalanches  was  not  the  immediately  enclos- 
ing country,  but  rocks  similar  to  it,  which  underlie  it  at  a  greater 
depth.  The  silver  and  gold,  it  may  be  suggested,  were  precipitated 
from  other  solutions,  and  at  a  period  other  than  that  which  saw  the 
deposition  of  the  nickel  and  cobalt.  The  precious  metals  were  prob- 
ably derived  from  a  deeper-seated  source ;  and  may  have  been 
leached  from  the  granite  which  underlies  the  schists  and  is  penetrated 
by  the  basic  eruptives.  In  both  cases,  the  various  metals  must  have 
come  from  a  depth  where  leaching  action  was  powerful,  and  from 
which  ascending  currents  brought  the  metallic  constituents,  the  sub- 
sequent precipitation  of  which  produced  valuable  ore-deposits. 


NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors 
or  communications  for  publication  as  "  Discussion,"  or  independent 
papers  on  the  same  or  a  related  subject,  are  earnestly  invited. 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Enterprise  Mine,  Rico,  Colorado. 

By  T.   A.  BICKARD,  STATE  GEOLOGIST,  DENVER,  COLO. 
(Colorado  Meeting,  September,  1896.) 

I. — HISTORICAL. 

Rico,  in  the  southwestern  corner  of  Colorado,  is  one  of  the 
productive  mining  centers  of  the  San  Juan  region,  so-called 
because  its  waters  drain  into  the  river  of  that  name,  which  is 
tributary  to  the  Colorado.  The  San  Juan  region  includes  the 
counties  of  Ouray,  Hinsdale,  San  Miguel,  Dolores,  San  Juan 
and  Montezuma.  It  is  traversed  by  a  network  of  picturesque 
mountain  ranges  on  whose  lofty  summits  there  rests  perpetual 
snow.  The  region  is  peculiarly  rugged,  and,  in  the  early  days 
of  its  development,  tested  to  the  full  the  hardihood  of  the  ad- 
venturers who  first  explored  its  canons  in  search  for  gold  and 
silver. 

A  prospecting  party,  guided  by  Jim  Baker,  scout  and  trap- 
per, penetrated  in  1861  this  part  of  the  territory  of  Kansas.  At 
that  time  the  country  was  in  the  possession  of  the  Ute  Indians. 
In  October,  1873,  by  the  Brunot  treaty,  they  ceded  to  the  United 
States  Government  the  richest  mineral-bearing  portion  of  their 
domain.  But  in  the  interval  much  prospecting  had  already 
been  done,  in  defiance  of  difficulties  among  which  snowslides 
and  redskins  were  the  most  noteworthy.  The  mountains  bor- 
dering the  Animas  and  its  tributaries  were  first  explored  by 
the  pioneers,  but  the  gathering  wave  of  immigration  soon 
swept  further  westward,  and  in  1864  a  guide  named  Robert 
Darling  brought  a  party  of  United  States  army  officers  and 
Mexicans  from  Santa  Fe  to  the  croppings  of  certain  lodes 
which  he  had  found  on  the  Dolores*  river.  This  party  erected 

*  If  the  Spaniard  devastated  the  countries  he  conquered,  he  at  least  left  a 
poetic  nomenclature  in  his  wake.  The  river  Animas  was  called  Rio  de  las  Ani- 
mas perdidas — "the  river  of  lost  souls,"  and  the  gloomy  magnificence  of  its  tu- 
multuous way  renders  the  name  appropriate.  Dolores,  Durango,  San  Miguel, 
San  Juan,  Ignacio,  Dulce,  Juniata,  etc.,  compare  well  with  Cripple  Creek,  Lead- 
ville,  Central  City,  Corkscrew,  Coke  Ovens,  etc. 

1 


THE   ENTERPKISE    MINE,   RICO,    COLORADO. 


FIG.  A. 


0  400          800          IgQO       1600 

Scale  of  Feet. 


MAP  SHOWING~THE  PROPERTY 
OF  THE 

ENTERPRISE    MINING   COMPANY 

AT  RICO,  COLORADO. 


THE   ENTERPRISE    MINE,   RICO,    COLORADO.  3 

an  adobe  furnace  and  spent  an  entire  summer  in  an  abortive 
attempt  to  smelt  the  ores,  the  outcrop  of  which  can  still  be 
seen  at  the  north  end  of  the  main  street  of  the  town  of  Rico, 
upon  claims  now  owned  by  the  Atlantic  Cable  Company.  In 
the  autumn  they  returned  to  Santa  Fe,  and  the  valley  was 
given  up  to  the  trappers  and  hunters,  who  found  beaver  along 
the  stream  and  bear  and  deer  on  the  hillsides. 

In  1869  another  expedition  arrived.  It  consisted  of  John 
Eckels,  William  Hill,  Pony  Whitmore  and  two  others,  all  of 
whom  had  made  their  way  from  the  Moreno  mines,  a  district 
near  Elisabethtown,  in  what  is  now  New  Mexico.  They  dis- 
covered several  large  lodes  near  the  site  of  the  present  settle- 
ment of  Dolores.  In  the  following  year,  Gus  Begole  came 
across  the  range  from  Silverton,  and  brought  an  assay-outfit 
with  him.  He  and  his  partner,  Eckels,  discovered  and  located 
the  Nigger  Baby  (now  Yellow  Jacket)  and  Dolores  (now  Aztec) 
mines.  They  sank  several  shafts  and  ran  several  drifts,  but  the 
ore  proved  too  low  in  value  to  meet  the  costs  of  treatment  and 
transportation,  and  they  abandoned  their  claims.  Others,  who 
came  from  time  to  time,  had  a  like  experience. 

In  1878,  John  Glasgow,  Charles  Hummiston  and  Sandy 
Campbell  found  their  way  northward  from  La  Plata  City. 
They  spent  the  summer  in  active  work,  and  located  the  Atlan- 
tic Cable,  Grand  View,  Phoenix,  Yellow  Jacket  and  other 
claims.  During  the  succeeding  winter  and  in  the  early  spring 
of  1879,  the  news  went  out  that  "  carbonates  "  had  been  found 
at  Rico,  and  a  second  Leadville  uncovered.  A  "  rush  "  set  in. 
In  the  fall  of  that  year  Messrs.  Jones  and  Mackay,  of  Comstock 
fame,  visited  the  camp  and  purchased  the  Grand  View  group 
of  mines.  Next  year,  1880,  the  boom  continued,  and  the  erec- 
tion of  a  smelter*  was  begun.  The  material  required  for  con- 
struction all  came  on  mule-back  over  the  ranges  from  Alamosa 
at  a  cost  of  16  cents  per  pound.  In  the  fall  the  furnaces  were 
blown  in  under  the  superintendance  of  Messrs.  Endlich  and 
Arnold. 

All  the  early  discoveries  of  this  district  centered  around 
Nigger  Baby  hill  and  the  valley  at  its  base.  In  1879,  however, 

*  That  smelter  still  exists.  It  has  afforded  many  well-known  metallurgists 
their  early  and  hard-bought  experience.  Its  history  would  present  an  amusing 
commentary  on  the  struggles  of  ill-digested  enterprises. 


THE   ENTERPRISE    MINE,    RICO,    COLORADO. 
Fig.  B. 


LEGEND 

Group  Tunnel  Level  thus 
Enterprise.  Laura  »     " 
Intermediate          »     » 
Contact  »     .. 

Limit  of  Contact  Slopes 


MAP  OF  THE 

ENTERPRISE    3IINES 

AND 

WORKINGS. 

E.  W.  Hunt,  Surveyor. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  5 

a  shipment  was  made  to  Swansea  from  a  discovery  by  Harry 
Irving  on  a  claim  located  further  south,  on  Newman  hill,  which 
is  like  a  footstool  to  Mount  Dolores.  This  event,  unimportant 
as  it  seemed  at  the  time,  marked  the  beginning  of  the  devel- 
opment which  more  than  ten  years  later  led  to  the  prolific  pro- 
duction of  gold  and  silver  out  of  the  workings  of  the  Enter- 
prise and  Rico-Aspen  mines. 

In  the  spring  of  1881  David  Swickhimer,  Patrick  Cain  and 
John  Gault  sunk  a  shaft  35  feet  deep  upon  their  Enterprise 
claim  on  Newman  hill.  This  work  was  undertaken  not  upon 
the  evidence  of  ore,  but  in  the  expectation  of  cutting  the  con- 
tinuation of  the  veins  successfully  worked  in  certain  claims 
further  south,  owned  by  the  Swansea  Gold  and  Silver  Mining 
Company.  Without  entering  into  a  detailed  description  of  the 
geological  structure  of  Newman  hill  it  is  necessary,  in  order 
to  make  the  early  story  of  discovery  clear  to  the  reader,  to  say 
that  the  true  rock  (sandstone  and  limestone)  is  overlain  by 
drift,  through  which  shafts  must  penetrate  before  reaching  the 
ore-bearing  formation.  The  veins  do  not  reach  the  present 
surface,  save  in  the  face  of  the  landslip  where  Harry  Irving 
first  detected  them.  The  three  owners  above  mentioned  traded 
their  claim  to  George  S.  Barlow  for  $300  worth  of  lumber. 
Barlow  continued  the  sinking  of  the  shaft  to  a  depth  of  146 
feet.  On  an  adjoining  claim,  named  the  Songbird,  another  miner, 
A.  A.  Waggener,  sank  a  shaft  to  the  depth  of  203  feet.  The 
latter  penetrated  through  the  drift  into  lime  shale ;  but  the  En- 
terprise shaft  did  not  at  that  time  reach  the  true  rock.  Both 
shafts  got  into  very  wet  ground.  In  the  meantime  the  Swansea 
workings  were  reported  to  be  impoverished  and,  finally,  ex- 
hausted of  ore.  It  was  also  said  that  the  veins  did  not  extend 
northward,  but  the  real  fact  was  that  cross-veins  had  faulted 
the  ore-bearing  veins  in  a  manner  to  be  rendered  clear  later  on 
in  this  account.  Newman  hill  was  discredited,  and  early  in 
1883  the  Enterprise  and  Songbird  shafts  were  abandoned. 

A  year  later,  Larned  and  Hackett  resumed  work  in  the 
Swansea  levels,  and,  by  mere  accident,  discovered  that  the  veins 
had  not  come  to  an  end,  but  were  simply  dislocated.  They 
prosecuted  development,  proved  the  continuity  of  the  ore  and 
made  large  shipments.  Their  success  induced  Waggener  and 
Barlow  to  relocate  their  abandoned  claims  late  in  1886.  But 


6  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

neither  of  them  had  any  capital,  and  they  were  unable  to  over- 
come the  heavy  flow  of  water.  In  December,  1886,  David 
Swickhimer  bought  out  Waggener's  interest,  acting  on  knowl- 
edge obtained  while  working  in  the  Swansea  mine,  which  had 
satisfied  him  that  the  veins  must  extend  into  the  Enterprise  and 
Songbird  claims.  In  March,  1887,  he  recommenced  the  sink- 
ing of  the  Enterprise  shaft.  In  May  he  acquired  one-half  of 
Barlow's  interest.  In  July  the  windlass  was  replaced  with  a 
steam-engine  and  a  pump.  All  this  time  Larned  and  Hackett 
were  drifting  rapidly  northward  and  threatened  soon  to  reach 
the  boundary  separating  their  territory  from  that  of  Swickimer 
and  Barlow.  Unless  the  two  latter  succeeded  soon  in  finding  a 
vein  in  place,  so  as  to  permit  a  valid  location,  the  claims  could 
be  successfully  disputed.*  They  therefore  hurried  the  sinking, 
and  in  spite  of  bad  luck,  floods  of  water  and  a  general  lack  of 
experience,  they  struck  ore  on  the  6th  of  October  at  a  depth  of 
262  feet.  The  first  assay  gave  2.1  ounces  of  gold  and  519.4 
ounces  of  silver  per  ton. 

This  ore  was  one  foot  thick  and  formed  part  of  a  "  flat  lode." 
In  the  light  of  later  developments,  this  discovery  is  known  to 
have  been  a  piece  ot  particular  good  fortune,  for  the  maps  of 
to-day  prove  that  it  was  the  edge  of  the  biggest  ore-body  ever 
found  on  Newman  hill,  and  that  a  shaft  put  down  20  feet  fur- 
ther east  would  have  missed  it.  This  was  the  first  evidence  of 
the  existence  of  a  flat  ore-deposit.  Swickhimer  thought  at 
first  that  it  was  merely  a  roll  in  the  Enterprise,  an  almost 
vertical  vein.  It  was,  however,  soon  proved  by  the  workings 
to  be  a  bedded  formation,  conformable  to  the  enclosing 

7  O 

country.  The  shaft  was  sunk  60  feet  below  this  "  con- 
tact," and  a  drift  was  run  westward  until  the  increased  seepage 
of  water,  in  the  following  spring,  proved  too  much  for  the 
pump,  and  caused  work  to  be  confined  to  the  contact.  In  July 
the  water  diminished,  drifting  was  resumed,  and  in  August,  at 
a  distance  of  118  feet  southwest  of  the  shaft,  the  Enterprise 
vein  was  at  last  intercepted.  The  ore  was  20  inches  thick  and 
assayed  3.2  ounces  of  gold  and  285.5  ounces  of  silver  per  ton. 
In  May,  1890,  the  Songbird  and  Enterprise  mines,  together 
with  much  adjoining  property,  were  acquired  by  the  Enterprise 

*  A  good  example  of  the  iniquitous  operation  of  our  absurd  mining  law. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  7 

Mining  Company,  the  operations  of  which  were  directed  by  the 
writer  from  March  1,  1894,  to  February  28,  1895. 

Fig.  A  shows  the  group  of  claims  forming  the  property,  and 
the  railway  connecting  them  with  the  town  of  Rico.  The  mine 
map  (Fig.  B)  indicates  the  complex  of  drifts  and  crosscuts 
which  follows  the  ramification  of  veins.  The  workings  aggre- 
gate 8  miles  in  length.  They  have  yielded  ore  whose  gross 
value  exceeds  $3,500,000.  Of  this  nearly  one-quarter  has  been 
gold,  the  remainder  silver.* 

Entrance  to  the  mine  is  made  by  the  Group  tunnel  which 
has  a  course  S.  56°  58'  E.,  and  consequently  cuts  the  ore-bear- 
ing veins  almost  at  right  angles.  Moreover,  since  its  line  cor- 
responds closely  to  the  strike  of  the  country,  it  intercepts  the 
veins  at  an  approximately  equal  depth  below  the  contact.  It 
would  do  so  without  variation,  but  for  the  step-faulting  which 
accompanies  the  vein-structure. 

The  tunnel  or  adit  is  2920  feet  long.  Near  the  entrance  the 
contact  is  210  feet  overhead,  at  the  breast  it  has  approached  to 
within  35  feet.  The  largest  drop  is  due  to  a  down  throw  on 
the  so-called  Leo  cross-vein. 

n. — THE  CouNTRY-EocK. 

The  Dolores,  as  it  flows  southward  from  the  town  of  Rico,  is 
overlooked  on  the  west  by  Mount  Expectation,  and  on  the  east 
by  Newman  hill.  The  river  has  eroded  its  own  way  and  does 
not  follow  the  line  of  a  fault.  The  Lower  Carboniferous  beds, 
which  form  both  its  bed  and  the  immediately  flanking  hillsides, 
can  be  traced  across  the  valley.  On  Newman  hill  they  are  for 
the  most  part  hidden  by  a  deposit  of  Quaternary  drift,  the 
maximum  thickness  of  which  is  about  400  feet,  diminishing 


*  The  analysis  of  representative  lots  of  ore  gave 

the  following  results  : 

First  class. 

Second  class. 

SiQz,                            29.  2  per  cent. 

50  to  55  per  cent. 

Mn,                               2.0        " 

6  to  10        " 

Fe,                             11.8       " 

6  to  10        " 

Zn,                             12.0       " 

5  to    7        " 

Pb,                              10.2        " 

2  to    3       " 

S,                               11.6       " 

5  to    8       " 

Au,                               0.87  oz.  per  ton. 

0.3  to  0.5  oz.  per  ton. 

Ag,                            221.50      "      " 

45  to  75        "      " 

The  first  class  was  mostly  contact-ore,  while  the  second  class  consisted  of  the 
bulk  of  the  product  of  the  verticals. 


8 

southwestward.  The  underlying  shales,  limestones  and  sand- 
stones contain  fossils  which  determine  their  stratigraphical  place. 
The  intrusions  of  porphyrite,*  both  plentiful  and  irregular  in 
form,  particularly  at  the  northern  end  of  Newman  hill,  afford 
an  explanation  of  the  metamorphism  of  the  sedimentary  rocks. 

The  country  enclosing  the  ore-deposits  consists  of  these 
shales,  limestones  and  sandstones,  having  a  strike  !N".  20°  "W. 
and  an  average  dip  of  10°.  They  are  thinly  bedded.  Single 
beds  are  not  extensive,  one  layer  dwindling  in  thickness  until 
it  dovetails  into  another.  Without  necessary  variation  in 
width,  the  composition  may  change  so  that  lime  graduates  into 
sandstone.  These  facts  indicate  that  the  sediments  were  laid 
down  in  estuaries  and  in  such  shallow  reaches  of  water  as  per- 
mitted of  swift  changes  in  the  conditions  of  sedimentation. 
The  fossil  remnants  are  of  a  kind  that  accords  with  this  view. 

The  foregoing  description  applies  especially  to  that  portion 
(about  200  feet  thick)  of  the  formation  to  which  the  mine- 
workings  are  practically  confined.  The  veins  do  not  penetrate 
upwards  beyond  the  horizon  known  as  the  "  contact,"  and  they 
become  barren  at  an  average  depth  of  about  150  feet  below 
that  horizon.  For  this  reason  the  overlying  rock  has  been 
merely  penetrated  in  sinking  to  the  ore-bearing  horizon,  and, 
similarly,  the  underlying  beds  have  only  been  pierced  by  one  or 
two  unsuccessful  shafts  and  bore-holes. 

The  beds  above  the  contact  consist,  in  ascending  order,  of: 

2  to  5  ft.  of  lime  breccia; 

A  thin  bed  of  soft,  crushed  sandstone,  which  rarely  reaches 
a  thickness  of  9  ft.,  averages  less  than  1ft.,  and  is  occasion- 
ally entirely  absent; 

*  The  following  notes  on  a  thin  section  of  this  rock,  a  hornblende-augite  por- 
phyrite, were  given  by  Mr.  R.  C.  Hills,  geologist  of  the  Colorado  Fuel  and  Iron 
Company. 

Macroscopic  Character. — The  rock  is  grayish  in  color,  and  shows  white,  opaque 
feldspar  (plagioclase),  evidently  much  kaolinized ;  also  small,  partly-altered 
green  hornblendes.  Apatites  are  occasionally  visible  under  the  lens. 

Microscopic  Character. — Under  the  microscope  the  feldspars  are  seen  to  be  largely 
altered  to  kaolin.  So  far  as  determinable  in  the  only  section  available,  they  are 
plagioclase.  The  green  hornblendes  are  largely  altered  to  chlorite.  Small  pale- 
green  augites  and  stout,  relatively  large  apatites  are  rather  numerous,  together 
with  ore  particles  (magnetite).  The  granular  groundmass  is  much  kaolinized, 
and  abundantly  distributed  through  it  are  grains  and  microlithic  crystals  of  feld- 
spar, also  kaolinized. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  9 

6  to  8  ft,  of  black  shale ; 

30  to  40  ft.  of  sandstone  beds,  and 

40  to  50  ft,  of  black  lime-shales. 

The  last  graduate  into  a  series  of  blocky  limestones,  the  es- 
carpments of  which  appear  on  the  face  of  Mount  Dolores.  In 
none  of  the  beds  of  this  series  have  profitable  ore-deposits  been 
found,  although  large  veins  of  calc-spar  traverse  them  at  inter- 
vals. 

The  contact  is  not  an  ore-measure  lying  between  two  persist- 
ent beds  of  shale  and  limestone,  as  has  been  stated.*  The 
composition  of  the  encasing  rocks  is  variable  because  of  the 
comparatively  brief  persistence  of  individual  members  of  the 
sedimentary  series.  It  may  be  said,  however,  that  the  ore  of 
the  contact  is  invariably  found  in  rock  which  has  undergone 
shattering.  An  appearance  of  undisturbed  solidity  is  occa- 
sionally given  by  later  cementation.  Several  raises  put  up  to 
the  contact  from  the  upper  main  level  of  the  mine  afford  sec- 
tions of  the  formation.  Two  are  quoted. 

No.  1.  No.  2. 

10  in.  of  compact  pulverulent,  2  ft.  of  brown  lime  breccia, 

lime,  6  in.  of  fine-grained  sand- 
14  in.  of  lime  breccia,  stone. 

2  in.  black  shale,  21  in.  dark  blocky  limestone, 

19  in.  limstone,  3  in.  black  soft  shale, 

12  in.  sandy  limestone,  28  in.  blocky  lime, 

10  in.  sandstone,  5  in.  laminated  sandstone, 

1  in.  parting  of  black  mud,  18  in.  black  shale, 

2  ft,  lime  shale,  1  in.  parting  black  mud, 

8  in.  crushed  lime,  15  in.  light  gray  limestone, 

25  in.  blocky  limestone,  1  in.  parting, 

10  in.  soft  sandstone,  58  ft.  sandstone, 

1  in.  parting  of  shale,  2  J  ft.  shale, 

Then  a  series  of  thin  beds  of  7  in.  sandstone, 

sandstone  aggregating   21  3  in.  shale, 

ft.  4J  ft.  sandstone, 

18  in.  light-colored  limestone,  2  in.  lime  shale, 

10  ft,  sandstone,  3  ft.  coarse  sandstone. 
Then  a  further  series  of  sandstones. 

*  J.  B.  Farish,  Proceedings  Colorado  Scientific  Society,  vol.  iv.,  p.  154. 


10 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


The  section  given  in  the  first  column  came  from  the  first 
raise  on  the  Jumbo  No.  3  upper  level,  the  second  from  a  raise 
on  the  Kitchen  vein  from  the  Enterprise  level  at  the  end  of  the 
cross-cut  between  raises  7  and  8,  Songbird.  The  linear  distance 
between  the  two  sections  is  only  900  feet.  Beyond  the  simi- 
larity of  the  breccia,  which  marks  the  "  contact,"  these  two 
sections  are  entirely  dissimilar,  and  it  seems  impossible  to  re- 
cognize any  continuity  in  the  stratification.  The  comparison 
serves  to  explain  the  statement  already  made  that  the  beds  of 
the  series  are  notably  non-persistent.  The  sketch  reproduced 
in  Fig.  1  represents  the  face  of  a  cross-cut  where  a  bed  of  sand- 
stone has  been  caught  in  the  act,  as  it  were,  of  merging  into 

a  bed  of  lime-shale. 

FIG.  1. 


Non-persistence  of  Beds. 

Further  sections  of  the  contact-horizon  will  be  given  when 
we  come  to  consider  the  ore-distribution  at  that  level. 

It  has  been  seen  that  below  the  contact  comes  a  series  of  very 
thin  lime  and  shale  beds,  interrupted  by  occasional  sandstone 
divisions.  These  beds  are  all  dark  in  color,  graduating  from 
coal-blackness  at  the  contact  to  dark  grays  at  a  distance  of  100 
or  150  feet  from  it.  As  the  contact  is  left,  the  sandstone  beds 
become  more  frequent,  their  grain  is  notably  coarser,  the  lime- 
stones become  less  shaly  and  more  blocky,  the  black  shale  is 
absent,  and  soon  the  workings  penetrate  into  thick  beds  of  a 
coarse,  light-colored  quartzitic  sandstone. 

One  or  two  shafts  have  been  sunk,  but  the  records  which 
have  been  kept  are  unfortunately  so  vague  as  to  be  useless  for 
the  purposes  of  a  geological  section.  The  Jumbo  shaft  pene- 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  11 

trated  524  feet  below  the  contact,  without  any  discovery  of  im- 
portance. The  Skeptical  shaft,  just  north  of  the  Enterprise 
property,  was  sunk  365  feet  in  porphyrite  and  then  penetrated 
15  to  20  feet  of  shales  and  limestone.  A  hore-hole  subse- 
quently put  down  in  the  bottom  of  this  shaft  went  through  200 
feet  of  shales  and  limestone  before  entering  quartzite,  wrhere 
operations  ceased.  The  Lexington  tunnel,  which  is  400  feet 
below  the  contact,  penetrates  the  Newman  hill  formation  for  a 
distance  of  2740  feet,  and  is  in  coarse,  light-colored,  hard  sand- 
stone for  most  of  its  length. 

There  has  always  been  much  surmise  regarding  a  certain 
undiscovered  "  second  contact."  It  has  been  the  cause  of  much 
nonsensical  mining.  The  Enterprise  Company,  in  1893,  sunk 
the  Jumbo  shaft  in  search  of  this  lower  ore-measure,  not  realiz- 
ing that,  owing  to  the  position  of  the  shaft  and  the  dip  of  the 
formation,  they  would  have  to  go  down  300  feet  below  their 


Fig.  la 


ibo  Shaft 


Scale,  150  feet  =1  inch  Group  Tunnel 

SECTION  THROUGH  JUMBO  AND  LAURA  SHAFTS. 

main  adit  before  they  would  be  even  level,  in  a  geological 
sense,  with  existing  northern  workings. 

This  piece  of  exploratory  work  was  badly  planned  and  proved 
without  result.  The  neighboring  company,  the  Rico-Aspen 
Consolidated  Mining  Co.  put  down  a  bore-hole,  which  was  as 
barren  of  encouragement.  The  "  second  contact "  of  Newman 
hill  is  a  vain  imagination.  A  hazy  idea  of  the  geology  of  Lead- 
ville,  blended  with  a  misconception  of  that  of  Rico,  has  caused 
the  growth  of  an  idea  having  no  facts  for  its  support.  It  was 
suggested  by  the  occurrence,  on  the  hills  north  of  the  town 
(above  the  village  of  Piedmont),  of  a  series  of  at  least  three  ore- 
bearing  contacts,  and  it  seemed  to  be  indicated  by  the  devel- 
opments in  the  Atlantic  Cable  mine.  But  deductions  from  this 
evidence  are  vitiated  by  reason  of  the  fact  that  the  valley  of  the 
Dolores,  near  the  north  of  the  town,  is  crossed  by  a  large  dike 
of  porphyrite,  marking  a  fault  which  breaks  the  continuity  of 
the  country  on  either  side. 


12         THE  ENTERPRISE  MINE,  RICO,  COLORADO. 

The  Atlantic  Cable  Co.'s  bore-hole  gave  the  following  down- 
ward section : 

Feet. 

Limestone,        .        .        */«.'-•»•       .        .        .        .        .       7 
Lead- and  zinc-ore,  .         .        .'        .      '  '.  '      .        .    '    ,y      .       4 
Limestone,        .  -^'V-  ?     .        .        .       '•.  :*'*i  •      /''•'••''       .       5J 
Lead  and  zinc-ore,  .         .         .       ;.        ?        •        .         .         .       5 

Limestone, .•        •        •        •        .13 

White  marble,          .         .  .    '**i         .         .         .         .20 

Zinc-blende  ore,        .........       3 

Specular  iron-ore 18 

Limestone,         ..........     43 

Porphyrite,       ..........       1 

Limestone, 25 

Porphyrite,        ..........       2 

Limestone,        ..........       3 

Mineralized  porphyrite,    ........       3 

Porphyrite, 21 

The  remaining  170  feet  of  the  hole  continued  in  quartzite. 
To  render  the  evidence  complete,  I  now  append  the  record  of 
the  Rico- Aspen  Co.'s  bore-hole.  This  was  sunk  20  feet  north- 
west of  the  Jumbo  vein,  between  raises  7  and  8,  at  a  point  85 
feet  below  the  contact.  It  was  begun  February  12,  and  fin- 
ished September  10,  1895.  From  the  collar  to  a  depth  of  481 
feet  the  drill  traversed  alternating  beds  of  limestone  and  sand- 
stone;  the  latter  becoming  coarser  as  depth  was  attained. 
From  481  to  541  feet  the  drill  traversed  porphyrite.  Between 
541  and  573  feet  the  rock  was  quartzite.  Then  porphyrite  con- 
tinued to  the  bottom  of  the  hole,  at  706  feet.  The  evidence 
afforded  by  these  borings  will  be  referred  to  after  other  mat- 
ters have  been  passed  in  review. 

III. — THE  ORE-OCCURRENCE. 

In  the  investigation  of  the  relation  between  the  ore-occur- 
rence and  the  rock-structure  it  is  found  that  there  are  two  dis- 
tinct systems  of  vein-fissuring.  One  series  of  veins  has  a 
N.E.-S.W.  strike  and  a  nearly  vertical  dip ;  and  this  series  is 
crossed  and  faulted  by  a  second  system,  having  an  approxi- 
mately IN",  and  S.  trend  and  a  flat  dip.  The  former  are  ore- 
bearing  and  are  called  "  verticals  "  or  "  pay-veins ;  "  the  latter 
are  barren  of  valuable  ore  and  are  termed  "  cross-veins."  Both 
series  fail  to  reach  the  present  surface,  save  where  deep  erosion 
has  occurred ;  because  in  coming  up  through  the  Carboniferous 


THE  ENTERPRISE  MINE,  RICO,  COLORADO.         13 

• 

formation  they  are  abruptly  terminated  in  their  near  approach  to 
a  certain  horizon  marked  by  the  occurrence  of  black  shale  and 
beds  of  crushed  lime.  This,  the  contact,  is  disturbed  by  the 
cross-veins. 

The  verticals  are  not  productive  immediately  under  the  con- 
tact. On  the  contrary,  when  within  a  distance  varying  from  5 
to  15  feet  from  that  contact  they  split  up  into  stringers,  which 
scatter  the  ore  so  as  to  render  exploitation  unprofitable.  Apart 
from  this  dispersion  of  the  vein,  the  total  amount  of  ore  which 
it  carries  is  also  decidedly  lessened.  The  plane  of  the  contact 
is  itself  ore-bearing ;  the  bodies  occurring  in  the  form  of  nar- 
row channels  ramifying  through  the  crushed  rock,  in  directions 
which  correspond  exactly  to  the  strike  of  the  veins  underneath. 
It  is  a  notable  fact,  moreover,  that  the  cross-veins,  barren  as 
they  are,  are  yet  related  to  ore-bodies  on  the  contact  as  rich  as, 
if  not  richer  than,  those  above  the  line  of  the  verticals. 

The  knowledge  of  the  relationships  just  outlined  has  proved 
vital  to  the  intelligent  exploration  of  the  mines ;  and  the  theo- 
retical consideration  of  them  is,  to  the  student  of  ore-deposition, 
highly  suggestive.  The  structure  of  the  formation,  on  account 
of  the  narrowness  of  the  veins  and  the  thinness  of  the  beds 
through  which  they  pass,  affords  within  the  space  of  a  few 
square  feet  sections  which  ordinarily  it  requires  acres  to  en- 
compass. The  coloring,  moreover,  of  the  minerals  accompany- 
ing the  ore  and  of  the  rocks  enclosing  it,  is  so  marked  as  to 
assist  the  ready  intepretation  of  structure,  and  enable  the  ob- 
server to  portray  them  by  pen  and  pencil.  For  these  reasons  the 
writer  has  endeavored  to  give  the  testimony  collected  by  him 
in  the  form  of  a  series  of  drawings,  rendering  much  comment 
unnecessary. 

IV. — THE  "  VERTICALS  "  OR  ORE-BEARING  VEINS. 

These  belong  to  the  simplest  type  of  ore-deposit.  They  are 
fractures  cutting  across  the  sedimentary  rocks  almost  at  right 
angles  to  the  bedding-planes.  They  have  a  simple  structure. 
Their  width  averages  less  than  a  foot;  they  are  built  along 
fault-lines,  are  sensitive  to  the  changes  in  the  encasing  rock, 
and  are  themselves  faulted  by  veins  of  later  formation. 

About  a  dozen  veins  have  undergone  noteworthy  develop- 
ment, and  of  these,  five  have  yielded  the  bulk  of  the  ore-pro- 


14 


THE   ENTERPRISE    MINE,   RICO,  .COLORADO. 


duction  of  the  mine.  The  Enterprise,  Jumbo  No.  2,  Jumbo 
No.  3,  and  Hiawatha  all  dip  to  the  northwest  at  angles  varying 
from  5°  to  15°  from  the  vertical;  the  Eureka  is  practically  ver- 
tical ;  while  the  Kitchen,  Swansea  and  Songbird  veins  have  an 
opposite  (southeast)  dip  and  a  flatter  angle,  viz.,  from  12°  to 
22°  from  the  vertical.  Their  strike  varies  between  50°  and 

FIG.  2. 


l-r 


pZSHET-j  SHALE  g^lVEIN 

A  Typical  Pay -vein  or  Vertical. 

65°  east  of  north,  the  Eureka  being  conspicuous  for  its  regu- 
larity. 

Fig.  2  is  a  typical  illustration  obtained  from  the  end  of  one 
of  the  levels.  The  vein  is  from  5  to  6  inches  wide  and  cuts 
the  country-bedding  at  a  right  angle.  It  will  be  noted  that  the 
ore  occupies  the  line  of  a  fault,  the  throw  of  which  is  7  inches ; 
the  direction  of  the  movement  which  caused  it  being  indicated 


15 


FIG.  3. 


West 


Scale,  X  in.- 1ft. 

f .'•':":'•'••  ••••"•  :•':•]  F1NE  SANDSTONE 

S90  RHODOCHROSITE  P 


East 


BICAN  BAJUHmCO.N.Y. 


L        1  QUARTZ  g-^ 

SONGBIRD  VEIN 

Scale,  |-inch  =  1  foot. 


COARSE  SANDSTONE 
I  BLENDE  AND  GALENA 


16 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


by  the  turning  up  of  the  bedding-planes  on  the  hanging-wall  of 
the  vein,  and  a  corresponding  bend  in  the  partings  on  the  foot- 
wall  side.     The  varied  texture  and  color  of  the  beds  of  sand- 
stone and  limestone  rendered  this  structure  very  distinct. 
Fig.  3  represents  the  Songbird  vein,  which  has  a  dip  op- 

FIG.  4. 


|-V.V:.:-I  SANDSTONE 


LIMESTONE 


\\^\'\  VEIN  QUARTZ  ^f  CLAY 

Vertical  and  Horizontal  Movements. 

posite  to  that  of  the  Jumbo  No.  3,  just  described,  The  drawing 
came  from  a  stope  about  30  feet  below  the  contact,  where  the 
vein  happened  to  be  entirely  encased  in  beds  of  sandstone.  A 
fault  is  evident.  Its  throw  is  about  28  inches.  The  ore  is 
9  to  12  inches  wide.  On  the  hanging  there  is  a  casing,  A  A, 
3  to  4  inches  thick,  which  follows  the  vein  throughout  the 
section.  This  casing,  of  dark  sandstone,  is  separated  by  a 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  17 

slight  selvage  from  the  outer  country,  but  graduates  gently 
into  the  vein-stuff  adjoining  it  on  the  east.  On  the  foot-wall 
there  is  a  marked  selvage,  accompanied  by  crushed  rock. 
Two  inclusions,  C  C,  of  sandstone  occur  within  the  ore.  The 
latter  is  banded  by  streaks  of  zinc-blende  and  by  ribbons  of 
rhodochrosite  within  the  quartz.  D  D  is  quartz.  At  B  B  the 
ore  has  been  slightly  dislocated. 

In  Fig.  4  more  complex  conditions  are  represented.  Two 
dislocations  of  the  country  are  evident.  The  vertical  break 
followed  by  the  ore-formation  has  a  throw  of  about  2  feet, 
while  the  lateral  fault,  evidently  of  later  occurrence,  has  caused 
a  disturbance  measured  by  9  inches  only.  It  will  be  noticed 
that  the  parting  separating  the  upper  fine-grained  sandstone 
from  the  bed  of  limestone  has  been  brought  into  line  with  that 
dividing  the  same  bed  of  lime  from  the  underlying  coarser 
sandstone.  This  coincidence  must  have  facilitated  the  subse- 
quent lateral  shifting  of  the  rocks.  Such  occurrences  are  fre- 
quently observable  in  the  mine. 

It  may  be  questioned  whether  the  movement  along  the  bed- 
ding took  place  before  or  after  the  ore  had  been  laid  down. 
There  is  evidence  elsewhere  in  the  mine  that  such  movements 
have  both  preceded  and  succeeded  the  vein-formation.  In  this 
case  it  preceded,  because  the  ore  is  seen  to  be  not  abruptly 
broken  off,  but  shaped  to  the  structural  conditions  created  at 
this  point  previous  to  its  precipitation. 

A  different  state  of  things  is  disclosed  in  Fig.  5,  which  rep- 
resents the  Jumbo  No.  2  vein,  as  seen  in  the  end  of  the  lower 
level.  Here,  as  usual,  the  ore  occupies  a  fault-fracture,  which 
has  dislocated  the  bedding  to  the  amount  of  20  inches ;  but,  in 
addition,  a  later  movement  along  coincident  partings  has  broken 
the  vein  and  thrown  it  about  a  foot.  The  ore  has  been  shat- 
tered, and  in  the  clay  accompanying  the  line  of  fault  there  are 
pieces  of  quartz  and  rhodochrosite,  evidently  due  to  this  shat- 
tering. The  quartz-veins,  unaccompanied  by  ore,  observable 
to  the  left  of  the  vein,  are  of  later  origin.  The  dike  of  por- 
phyrite  will  be  referred  to  elsewhere. 

In  Fig.  6  a  similar  later  movement,  but  this  time  in  a  ver- 
tical direction,  is  illustrated.  The  Jumbo  No.  3  vein,  here 
shown,  follows  a  fault  the  throw  of  which  is  about  2  feet. 
Since  the  ore  was  laid  down  a  later  shifting  of  the  country  has 

2 


18 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


been  accompanied  by  the  formation  of  a  fracture,  which  ap- 
proximately follows  the  line  of  weakness  of  the  older  move- 
ment, and  breaks  across  the  ore  lying  in  its  path.  The  amount 
of  this  dislocation  cannot  be  measured  with  certainty;  it  is 

probably  slight. 

FIG.  5. 


LIMESTONE 
fVV^PORPHYRITE 


'\VVJVEIN   QUARTZ 


Fault  along  Bedding-plane. 

The  veins  are,  as  to  their  size,  behavior  and  ore-bearing  char- 
acter, very  sensitive  to  the  structure  of  the  enclosing  rock. 
They  flatten  when  traversing  lime,  the  increased  deviation 
from  the  vertical  being  accompanied  by  a  diminution  of  ore. 
Even  in  those  cases  where  the  actual  width  may  not  decrease 
the  percentage  of  valuable  minerals  does.  In  sandstone  they 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


19 


usually  straighten  up,  and  are  marked  by  an  enrichment. 
When  crossing  a  parting  between  the  beds  an  offset  of  ore  is 
often  formed  underneath  the  parting.  Some  of  these  charac- 
teristics are  illustrated  in  Figs.  7  and  8,  both  representing  the 
Enterprise  vein.  In  both  the  faulting  along  the  ore-break  can 
be  measured,  since  the  dislocated  portions  of  the  same  bed  are 
similarly  lettered. 

FIG.  6. 


LIMESTONE 
>/'-'!  VEIN 

Later  Movement  along  Original  Fracture. 

Among  the  miners  it  was  the  common  saying  that  "  the  vein 
makes  ore  in  sandstone,"  but  my  observations  did  not  quite 
confirm  this  generalization.  When  traversing  lime  the  veins 
tend  to  split  up  into  stringers,  and  this  is  the  case,  to  a  lesser 
degree  perhaps,  in  sandstone.  On  the  whole,  my  experience 
was  that  unlike  walls  give  the  best  environment  for  rich  ore, 


20 


THE  ENTERPRISE  MINE,  RICO,  COLORADO. 


and  that   a  footavall  of  sandstone  with  a  hanging  of  lime  is  a 
particularly  favorable  combination. 

In  some  cases  comparatively  modern  shiftings  of  the  country 
are  evidenced.  Thus  in  Fig.  7  the  flattened  part  of  the  vein, 
E  F,  formed  along  the  shale  band,  is  crushed,  and  it  is  my  be- 
lief that  this  was  caused  by  a  movement  along  the  bedding 


FIG.  7. 


PC"J  LIMESTONE 


I:  :"::':|  SANDSTONE 


MUD 


|^g%:|  SHALE  |j_\JVEIN 

Vein  Flattening  along  a  Shale-bed. 

long  subsequent  to  the  formation  of  the  vein  itself.  The 
stringers,  G  G,  are  also  of  late  origin,  and  are  composed  of 
barren  quartz  dissimilar  to  the  gangue.  In  Fig.  8  there  is  a 
similar  jog  in  the  vein,  but  in  this  case  no  crushing  or  disturb- 
ance is  suggested. 

Pronounced  selvages  are  not  characteristic  of  these  veins. 
When  noticeable  they  are  usually  in  lime-beds.     In  sandstone 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


21 


they  are  comparatively  infrequent,  and  the  absence  of  a  parting 
causes  the  ore  to  separate  with  difficulty  from  the  sandstone, 
into  which  it  merges  in  such  a  manner  as  to  cause  the  miners 
to  say  that  it  is  "  frozen  "  to  it.  A  casing  of  sandstone  is  occa- 
sionally seen  when  the  vein  is  entirely  enclosed  by  lime,  prov- 
ing that  the  sandstone  must  have  been  shorn  off  upper  beds  in 


FIG.  8. 


•'.•SANDSTONE 


VEIN 


Influence  of  Encasing  Rock  upon  Behavior  of  Vein. 

the  course  of  that  movement  which  determined  the  existence 
of  the  vein.  This  feature  is  illustrated  in  Figs.  9  and  10. 
The  first  of  these  represents  the  Jumbo  No.  3  vein,  which  in 
this  instance  is  identified  with  a  fault  of  about  3  feet  throw. 
On  the  foot-wall  the  ore  is  divided  from  the  country  by  a  clay 
selvage,  but  on  the  hanging  there  is  no  such  parting.  Toward 
the  bottom  of  the  section  the  vein  exhibits,  on  its  hanging-  wall, 


22  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

FIG.  9. 


RHODOCHROSITE 


g^g  CRUSHED  ROCK  | 

( 3  QUARTZ 

JUMBO   NO.  3  VEIN 

Scale,  | -inch  =  1  foot. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  23 

FIG.   10. 


J^      LIMESTONE 


RHODOCHROSITE 


CRUSHED  ROCK 


EUREKA  VEIN 

Scale,  ^f-inch  =  1  foot. 


24  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

a  casing  of  country  which  changes  from  sandstone  (A)  to  lime 
shale  (B)  in  accordance  with  the  succession  of  similar  adjacent 
beds.  The  ore  is  distinctly  ribboned  by  a  symmetric  alterna- 
tion of  vari-colored  minerals.  D  is  quartz.  The  vein  is  bi- 
laterally symmetrical  on  either  side  of  a  central  line  marked 
by  vugs  or  cavities,  C  C,  which  are  encrusted  with  quartz 
crystals.  The  blende  on  each  side  of  these  vugs  occurs  in  a 
curiously  spotty  manner,  suggesting  brecciation.  The  smaller 
vein,  E  E,  consists  of  barren  quartz  and  rhodochrosite.  It  is 
of  apparently  later  origin. 

In  Fig.  10  we  have  a  very  striking  example  of  this  ribboned 
structure,  to  be  discussed  later  on.  For  the  present  attention 
is  directed  to  the  sandstone  casings  which  follow  the  walls  of 
the  vein.  That  on  the  hanging  (F  F)  is  scarcely  an  inch  wide, 
and  has  no  appreciable  selvage  separating  it  from  the  outer 
country.  That  on  the  foot-wall,  A  A,  varies  in  thickness  from 
1 J  to  2f  inches,  has  a  distinct  parting  dividing  it  from  the  coun- 
try, and  is,  moreover,  marked  by  a  dark  streakiness,  suggesting 
incipient  ore-formation.  In  both  cases  these  casings  graduate 
gently  into  the  adjacent  vein-stuff. 

Each  vein  follows  a  fault-fracture.  The  shifting  of  the  coun- 
try is  not  likely  to  have  been  limited  to  a  single  line  of  fault- 
ing, and  it  is  found  that  just  as  the  series  of  "  verticals  "  indi- 
cate contemporaneous  and  approximately  parallel  movements, 
so  there  are  also  other  minor  shiftings  sympathetic  to  these, 
unaccompanied,  it  may  be,  by  ore,  and  therefore  unexplored  by 
the  miner.  Such  subordinate  faults  are  occasionally  seen  close 
to  the  vein.  Fig.  11  is  a  section  of  the  Jumbo  Fo.  3  in  a  stope 
where  it  was  non-productive,  being  represented  merely  by  a 
barren  quartz  vein,  carrying  a  little  rhodochrosite,  but  no  valua- 
ble sulphides.  Two  lines  of  faulting,  A  A  and  B  B,  are  evi- 
dent. The  vein  first  follows  one  of  these  fault  planes  and 
then  deviates  along  cross-joints  until  it  meets  the  other,  5  feet 
further  west,  which  it  then  accompanies.  Both  fault-lines  are 
marked  by  a  selvage.  The  ore  lies  on  the  under  side.  The 
main  lode  (DD)  reappears  (along  BB)  5J  feet  lower  down. 
Deeper  still  it  crosses  over  to  the  western  fault,  as  its  branch 
had  previously  done,  and,  uniting  with  the  latter,  forms  a  strong, 
rich  vein,  which  continues  undisturbed  to  a  further  depth  of  30 
feet,  when  another  irregularity  breaks  its  continuity. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


25 


Fig.  12  affords  farther  evidence.  In  this  case,  as  in  the  last, 
the  vein  is  seen  where  it  is  small  and  poor.  Under  such  con- 
ditions its  structure  is  more  readily  discernible,  because  enrich- 
ment and  enlargement  generally  produce  confused  outlines  and 
are  accompanied  by  a  generous  mineralization,  destructive  of 


Vein  Changing  from  one  Fault-plane  to  Another. 

definition.  Hence  the  stopes  most  instructive  to  the  scientific 
investigator  are  least  pleasing  to  the  mine  manager.  In  this 
section  there  are  two  veins,  both  small,  of  which  the  western 
may  be  regarded  as  a  mere  off-shoot.  Two  dislocations  and 


26 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


several  minor  disturbances  of  the  country  are  noticeable.  The 
western  quartz-seam  occupies  a  fault  of  a  few  inches,  which  dies 
out  into  a  mere  distortion  of  the  bedding ;  the  larger  vein  is 
identified  with  a  fault  having  a  throw  of  2  J  feet.  The  bending 


SANDSTONE  3dME  r-     SHALE 

SANDY  LIME    Q^  QUARTZ 

CRUSHED  ROCK       —  SELVAGE 

Double  Dislocations. 


of  the  edges  of  the  beds  as  they  abut  against  the  vertical  quartz- 
veins  is  very  marked.  Slight  shiftings  along  bedding-planes  are 
indicated  by  the  behavior  of  the  small  stringers  traversing  the 
country. 

The  veins  are  built  up  of  many-colored  minerals,  which  give 
them  a  rare  beauty,  and  serve  also  to  accentuate  their  structure. 


FIG.  13. 


Scale  of  feet 


FIG.  14. 


K    £ 


-ErTTTTi  LIM!>          A- .-.•..•.:•>  SAND-          /.  ...,.^_.  >      SANDY  , — ^^^ 

>"->']  STONE        l^Ll.^i;  STONE          [^-j,] LIMESTONE     <^S> 

aCROCKHED      C^QSEAMT3Z  C^^VE.N 

The  Jumbo  No.  3  Vein. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  29 

Rhodochrosite  and  quartz  enclose  the  sulphides  of  zinc,  lead, 
iron,  copper  and  silver  in  the  form  of  galena,  blende,  iron  and 
copper  pyrites,  argentite  and  stephanite.  Native  gold  and 
native  silver  both  occasionally  accompany  the  argentite.  A 
banded-  or  ribbon-structure  is  frequently  brought  about  by  the 
alternation  of  quartz,  rhodochrosite  and  the  sulphides.  This 
structure  assists  the  breaking  of  the  ore,  which  will  often  part 
in  ribbons  within  itself  more  readily  than  it  can  be  detached 
from  the  encasing  country.  Fig.  25  illustrates  a  typical  piece 
of  vein-stone.*  The  gentle  graduation  of  ore  into  country  is 
noteworthy.  The  banding  due  to  the  rhodochrosite  is  a  dis- 
tinguishing feature,  while  the  inclusion  of  portions  of  sand- 
stone and  the  comb-structure  of  the  quartz  are  additional  testi- 
mony as  to  the  origin  of  the  ore,  which  will  be  discussed  under 
another  heading. 

Much  more  might  be  said  concerning  the  behavior  of  these 
veins ;  but  sketches  of  the  actual  occurrences  are  better  than 
verbal  description.  Fig.  13  shows  the  Jumbo,  No.  3  lode,  as 
seen  in  the  stopes  of  the  mine.  The  vein  structure  is  illustrated 
for  a  height  of  sixteen  feet.  It  will  be  observed  that  the  vein 
follows  a  line  of  fracture  which  has  faulted  the  country. 
The  vertical  dislocation  measures  2  J  feet,  and  is  rendered  eas- 
ily evident  by  the  partings  of  shale  which  separate  alternating 
sandstone  and  limestone-beds.  Following  the  section  down- 
ward, the  ore  is  about  14  inches  wide  at  the  top,  opposite  A, 
and  is  distinctly  ribboned  with  bands  of  quartz,  rhodochrosite 
and  zinc-blende,  the  last  being  also  mixed  with  galena.  The 
vein  continues  fairly  uniform  for  five  feet,  and  is  then  inter- 
rupted by  a  break  opposite  B,  which  indicates  that  the  country 
has  been  shifted  to  the  right  for  a  distance  of  six  inches.  This 
movement  took  place  at  a  point  where  a  coincidence  occurs  be- 
tween the  partings  between  two  sandstone-beds  on  one  side  and 
lime-sandstone-beds  on  the  other.  Below  this  point  the  vein 
opposite  C  is  less  regular,  and  divides  into  two  branches,  of 
which  the  eastern  carries  all  the  pay  ore,  the  western  being 
merely  rhodochrosite  and  quartz.  The  latter,  from  its  compo- 
sition and  structure,  suggested  to  me,  at  the  time,  that  it  was  of 
later  origin  than  the  ore-bearing  vein.  Opposite  D,  four  feet 

*  For  a  discussion  of  the  evidence  afforded  by  this  drawing  the  reader  is  re- 
ferred to  the  author's  paper  entitled  "Vein- Wall,"  Trans.,  xxvi.,  193. 


Fi«.  15. 


A   


C,KE  ROCK  LIMESTONE 


FIG.  16. 


Downward  Continuation  of  Fig.  15,  Constituting  Section  of  Jumbo 
No.  3  Vein  through  Successive  Stopes. 


32          THE  ENTERPRISE  MINE,  RICO,  COLORADO. 

below  the  last  break,  another  occurs,  a  clean  transverse  fracture, 
accompanied  by  scarcely  any  shifting.  This,  too,  is  found 
where  partings  on  opposite  sides  are  so  placed  as  to  very  nearly 
make  a  continuous  plane.  The  vein  has  been  slowly  diminish- 
ing, and  opposite  E  is  only  8  inches  wide.  It  continues  to 
dwindle.  Independent  little  quartz  stringers  to  the  right  sug- 
gest disturbed  ground.  The  vein  decreases  to  a  mere  thread 
and  ends  in  a  soft  shale  parting,  Gr,  two  inches  wide.  But  other 
more  interesting  features  demand  notice.  The  ore  no  longer 
clings  to  the  left  or  western  side  of  the  faul1>fracture,  which  de- 
termined the  original  vein-formation.  Moreover,  its  course 
downward  is  abruptly  terminated.  Several  fragments  of  ore  in 
the  shale  band  lead  naturally  to  the  continuation  of  the  vein, 
discovered  to  be  18  inches  to  the  east.  Here,  opposite  G,  the 
country  has  been  shifted  by  a  movement  equal  to  about  1J 
feet;  but  the  behavior  of  the  vein,  especially  the  bending  of 
the  ore  near  the  points  of  fracture,  suggests  that  the  dislocation 
of  the  country  took  place  before  the  vein  wTas  formed.  The 
broken  fragments  indicate  later  movement  also.  Two  feet 
lower  the  vein  is  fractured  and  slightly  dislocated.  Below  this 
point  the  ore  widens  to  8  inches,  and  so  passes  out  of  view. 

The  conditions  represented  in  Fig.  14  existed  in  the  stopes 
upon  the  same  vein,  about  one  hundred  feet  further  north  on  the 
strike.  It  is  particularly  interesting  as  illustrating  the  changes 
not  only  in  the  vein  but  in  the  individual  numbers  of  the  series 
of  sandstone,  shale  and  limestone-beds  through  which  the  vein 
passes.  Commencing  at  the  top,  K,  of  the  section,  the  ore  is 
seen  to  be  seven  inches  wide.  About  1J  feet  lower,  opposite 
L,  there  is  an  incipient  break  in  the  vein,  not  sufficient  to  part 
it.  At  five  feet  from  the  top,  opposite  M,  a  rupture  has  taken 
place,  accompanied  by  only  a  very  slight  displacement.  Eleven 
inches  lower,  opposite  X,  there  is  another  break.  M  and  IS"  cor- 
respond to  B  in  Fig.  13.  The  ore  here  is  9  to  10  inches  wide. 
The  vein  is  well  defined  and  nearly  vertical.  Opposite  O,  three 
feet  below  N",  there  is  a  more  serious  break.  The  vein  is  dis- 
placed its  own  width,  and  for  a  height  of  six  inches  is  broken 
into  several  definite  fragments.  This  severe  shattering  is  due 
to  the  fact  that,  in  the  absence  of  coincident  partings,  no  clean 
horizontal  shifting  of  the  country  took  place,  but  the  movement 
became  more  of  a  distortion.  Compare  the  corresponding  break 


THE  ENTERPRISE  MINE,  RICO,  COLORADO.          33 

in  Fig.  13,  opposite  D.  The  vein  now  decreases,  as  in  Fig.  13, 
and  leaves,  opposite  P,  the  foot-wall  of  the  main  fault-fracture. 
Opposite  Q  the  ore  is  about  1J  inches  wide  and  two  partings 
exactly  coincide,  so  that  the  horizontal  shifting  of  the  country 
is  expressed  by  a  clean-cut  fault  in  the  vein  amounting  to  a  dis- 
placement of  1J  feet.  A  piece  of  ore  occurs  in  the  clay-seam, 
midway  between  the  divided  parts  of  the  vein.  Below  this  the 
ore  increases.  Opposite  R  there  is  an  incipient  fracture,  cor- 
responding to  H  in  Fig.  13.  The  ore  then  widens  steadily,  and, 
as  it  leaves  the  section  at  S,  has  a  width  of  about  one  foot, 
neatly  ribboned.  In  this  section  the  vertical  throw  along  the 
fault-fracture  followed  by  the  vein  is  a  little  less  than  in  Fig. 
13. 

In  Figs.  15  and  16  there  is  a  representation  of  the  same  vein 
as  seen  in  a  series  of  six  stopes  covering  a  vertical  height  of  33 
feet.  These  stopes  were  at  least  two  hundred  feet  north  of  the 
place  illustrated  in  Fig.  14,  but  in  the  same  horizon  of  country- 
rock.  The  lime  and  sandstone  at  the  top  of  Fig.  15  can  be 
identified  with  the  beds  P,  Q  and  W  in  Fig.  14,  and  with  Z  and 
U  in  Fig.  13. 

At  the  top  of  Fig.  15,  opposite  A,  the  vein  is  only  5  inches  wide, 
but  is  built  up  of  rich  sulphides,  zinc-blende  and  galena.  A 
little  lower,  opposite  B,  the  ore  leaves  the  foot-wall  of  the  fault- 
fracture  and  then  undergoes  a  dislocation  of  over  two  feet.  This 
movement  along  the  bedding  of  the  country  occurs  where  part- 
ings coincide.  On  the  west  the  plane  of  movement,  C,  is  not 
accompanied  by  much  selvage,  but  eastward  there  is  a  seam  of 
clay  widening  to  3  or  4  inches  in  thickness.  Incidentally  the 
want  of  correspondence  in  the  composition  of  the  country  on 
the  two  sides  of  the  vein  attracts  attention  to  the  fact  that  it 
follows  a  fault-fracture,  the  vertical  throw  of  which  is  three  feet. 
Opposite  D,  one  foot  below  the  break,  C,  the  ore  exhibits  what 
miners  call  a  "  splice,"  that  is,  one  distinct  band  of  ore  thins 
out  and  another  at  the  same  time  commences  to  appear.  The 
vein  opposite  E  is  about  six  inches  wide,  and  rich.  Just  above 
it  was  very  poor  and  quartzose.  Nothing  noteworthy  occurs 
until,  three  feet  lower  (F),  another  splice  is  seen.  The  vein  is 
still  small  but  fairly  rich,  and  continues  thus  very  uniformly  for 
another  five  feet,  when  (Gr)  several  features  attract  attention. 
The  vein  appears  fractured,  although  not  separated,  and  abuts 

3 


34  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

against  a  dike  of  porphyrite  nearly  one  foot  wide,  which  forms 
the  hanging-wall  of  the  ore  for  a  distance  of  five  feet  (G,  Fig. 
15,  to  H,  Fig.  16).  "When  traced  up  and  down  the  series  of 
stopes  it  was  found  to  cease  in  both  directions  and  to  be  there- 
fore an  intruding  tongue.  Its  behavior  is  clearly  shown  in  the 
drawing,  beginning  opposite  X,  Fig.  15,  and  ending  opposite  Y, 
Fig.  16.  It  varies  little  from  a  uniform  width  of  slightly  less  than 
afoot,  except  for  a  short  distance  (H  to  W),  where  it  is  squeezed 
to  a  mere  thread  a  few  inches  wide.  The  porphyrite  is  evi- 
dently very  sensitive  to  the  structure  of  the  country-rock 
into  which  it  has  thrust  itself.  Opposite  G  the  ore  is  about  7" 
inches  wide.  It  continues  so  for  four  feet  downward,  when  (K) 
another  splice  occurs  and  the  vein  widens.  For  the  next  six 
feet  the  ore  varies  from  6  to  12  inches,  and  is  then  (L)  slightly 
dislocated.  Below  this  the  vein  widens  steadily  and  develops  a 
beautiful  ribbon-structure,  passing  out  of  the  section  (M)  with  a 
thickness  of  14  inches.  At  the  bottom  of  the  section  an  in- 
structive feature  is  presented.  The  ore-bearing  vein  leaves  the 
main  fault-fracture  (here  shown  by  a  line  to  the  right),  and 
pitches  slightly  to  the  west.  This  is  only  temporary.  Lower 
down,  outside  the  section  here  shown,  it  turns  back  and  resumes 
its  course  along  the  fracture  which  determined  its  existence.  It 
will  be  noted  that  the  ore  in  leaving  the  main  fault-line  (about 
opposite  Y),  follows  a  line  of  minor  fracturing  which  shows  a 
slight  but  evident  dislocation  also. 

These  four  sections,  Figs.  13  to  16,  show  how  the  behavior 
of  the  vein  is  determined  by  the  structure  of  the  enclosing 
rock.  The  fracturing  through  the  country,  which  opened  a 
possible  channel  for  the  circulation  of  the  mineral-bearing 
waters,  was  continuous  but  irregular.  The  irregularity  was 
due,  in  the  first  place,  to  the  varying  composition  of  the  beds 
through  which  the  fracture  passed.  That  fracturing  was  ac- 
companied, as  we  have  seen,  by  a  vertical  displacement  of  from 
two  to  three  feet.  The  direction  of  the  throw  is  beautifully 
evidenced  by  the  bent  edges  of  the  partings  in  the  country  on 
either  side ;  on  the  hanging,  upward ;  on  the  foot-wall,  down- 
ward. 

The  horizontal  shiftings  which  now  break  the  vein  occurred 
in  part  before  ore-deposition,  but  mostly  afterward.  The  later 
movements  were  also  the  parents  of  the  quartz-stringers  which 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  35 

now  fringe  the  vein,  as  at  C  and  F  in  Fig.  13,  and  M.  and  P. 
in  Fig.  14.  They  represent  the  healing-action  of  later  solu- 
tions, circulating  along  a  reopening  of  the  old  passage-ways. 

The  three  sections,  Figs.  13, 14  and  15,  illustrating  the  same 
horizon  in  the  country,  at  considerable  distances  apart,  serve  to 
prove  how  individual  members  of  the  sedimentary  series  change 
in  composition.  The  two  beds,  E  and  Z,  both  limestone,  in 
Fig.  13,  become,  in  going  northward,  the  two  beds,  P  and  Q, 
one  limestone  and  one  sandy  lime.  In  Fig.  14  the  relative 
thicknesses  have  changed.  Again,  in  Fig.  15,  the  same  beds, 
now  seen  200  feet  further  north,  are  to  be  identified  in  the 
single  bed  of  limestone  extending  from  A  to  C.  The  under- 
lying sandstone  also  shows  variations  at  the  different  points. 
It  is  noteworthy,  at  the  same  time,  that  the  vein  acts  much  in 
the  same  way  when  traversing  identical  beds  at  different  points. 

The  subsidiary  fracturing,  seen  in  Fig.  15,  to  the  east  of  the 
vein,  between  C  and  G,  is  instructive.  That  this  structure 
usually  accompanies  vein-faulting  I  certainly  believe.  The 
breast  of  a  slope  or  the  face  of  a  drift  rarely  exhibits  it,  because 
mining  does  not  require  that  the  ground  should  be  broken  for 
a  width  necessary  to  make  it  visible.  This  structure,  the  sheet- 
ing of  the  country,  is  very  marked  at  Cripple  Creek,  in  Colo- 
rado, and  is  the  origin  of  parallel  and  multiple  veins. 

Y. — THE  CROSS- VEINS. 

These  veins,  although  non-productive,  play  an  important  part 
in  mining  operations,  because  they  dislocate  the  ore-bearing 
"  verticals,"  and  are  themselves  related  to  extensive  ore-bodies 
on  the  contact.  The  picture  they  present  is  that  of  white  bands 
of  crushed  quartz,  cutting  through  everything,  as  distinguished 
from  the  verticals,  which  are  like  pink  ribbons  of  rhodochrosite, 
traversing  the  sedimentaries  with  difficulty  because  of  their 
faulting  by  these  cross-veins. 

The  latter  are  built  upon  fault-lines  marking  movements 
greater  in  extent  than  those  accompanying  the  older,  ore-bearing 
fractures.  They  are  essentially  quartz-veins.  A  variable 
amount  of  crushed  country  accompanies  the  quartz.  Rhodo- 
chrosite and  valuable*  sulphides  are  notably  absent.  When 

*  Many  assays  were  made  of  the  pyrites  from  cross-veins  encountered  in  cross- 
cuts. Traces  of  gold  and  4  to  8  ounces  of  silver  were  about  the  best  results.  Oc- 


36          THE  ENTERPRISE  MINE,  RICO,  COLORADO. 

seen,  they  represent  broken  fragments  of  pay-veins  traversed 
by  the  path  of  the  cross-vein.  Next  to  quartz,  iron  pyrites  is 
their  most  characteristic  mineral.  The  pyrite  is  in  a  crumbly, 
easily  disintegrated  state,  very  unlike  the  solid  crystalline  con- 
dition in  which  it  appears  amid  the  ore  of  the  verticals.  Some- 
times no  foreign  minerals  are  present  in  notable  quantity,  and 
the  cross-vein  is  simply  a  seam  of  crushed  country,  softening 
into  mud.  This  the  Cornishman  would  call  "  fluccan." 

Fig.  17  represents  a  cross-vein  in  the  breast  of  a  drift  on  the 
Jumbo  "No.  3  vein,  which  had  met  the  cross-vein  and  had  been 
faulted  by  it.  The  Jumbo  vein  was  intercepted  by  this  drift  8 
feet  further  ahead.  Three  breaks  are  noticeable,  each  marked 
by  faulting.  The  cross-vein  itself  lies  between  two  unlike  beds 
of  lime,  marking  a  fault  which  evidence  elsewhere  along  the 
drift  showed  to  be  6  feet.  The  lime  on  the  foot-wall  is  sepa- 
rated from  a  series  of  thin  beds,  exhibiting  a  good  deal  of 
variety,  by  a  curving  line  of  selvage,  following  a  fault  whose 
throw  is  4  feet.  Then  come  beds  of  shale,  crystalline  lime  and 
sandstone,  traversed  by  a  dislocation  of  10  inches.  In  each  case 
the  down-throw  is  on  the  hanging-wall.  The  cross-vein  is  almost 
vertical  and  carries  fragmentary  rhodochrosite  torn  from  the 
Jumbo  vein. 

Fig.  18  illustrates  another  cross-vein  in  the  act  of  cutting 
through  the  Jumbo  vein.  The  line  of  the  former  is  deflected 
in  breaking  through  the  latter.  To  the  left  the  series  of  beds 
consists  of  blocky  lime,  lime  shale,  broken  lime,  limestone, 
black  shale,  closely  laminated  lime  and  light  gray  sandstone. 
On  the  right  this  series  is  seen  to  be  succeeded  by  beds  of  dark 
sandstone.  The  fault  along  the  cross-vein  is  4  J  feet,  obliterating 
the  displacement  which  must  have  accompanied  the  line  of  the 
ore-bearing  vein.  The  latter  is  thrown  its  own  width,  10  inches. 
It  has  been  shattered  by  the  cross-vein,  but  appears  to  have 
been  repaired  and  reconsolidated  (since  its  displacement)  by 

casionally  good  assays  were  obtained,  but  the  pieces  from  which  these  samples 
came  were  invariably  marked  by  the  presence  of  fragments  torn  from  the  pay- 
veins.  Nevertheless,  from  a  scientific  standpoint,  pyrite  containing  a  few  ounces 
of  silver  is  as  much  ore  as  blende  or  galena,  carrying  much  higher  values.  In  this 
connection  it  may  be  added  that  the  pyrite  of  the  verticals  is  not  notably  silver- 
or  gold-bearing  unless  admixed  with  copper  pyrites,  blende  or  galena.  The 
pyrite  and  quartz,  whether  in  the  cross-veins  or  the  verticals,  is  not  a  sign  of 
valuable  ore. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


37 


healing  seams  of  quartz,  which  now  ramify  through  the  pre- 
viously hroken  rhodochrosite.  This  cross-vein  was  distant  28 
feet  from  the  one  described  above. 

The  comparatively  small  scale  of  the  rock-formation  affords 
many  excellent  illustrations  of  phenomena  usually  requiring 

FIG.  17. 


BANKNOTE  CO. N.V. 


j^17]  LIMESTONE  \^\  QUARTZ  \. 

(X°tfI^LVAGE  £2]  RHODOCHROSITE 

C::;T-j  SANDSTONE  g^T]  SHALE 

[f|U  CRUSHED  COUNTRY 

A  Cross-vein  in  Limestone. 

large  areas  for  their  exemplification.  Some  of  the  dislocations 
are  so  slight  that  they  can  be  seen  to  die  out  in  mere  distortions. 
See  Figs.  19  and  20.  The  former  is  particularly  instructive. 
It  shows  the  sides  of  a  cross-cut  which  joins  the  workings  on 
the  Hiawatha  and  Enterprise  veins.  Near  the  floor  of  the  cross- 
cut there  is  a  fault  of  about  5  inches  which  follows  a  seam  of 


38 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


clay  nearly  1  inch  thick.     This  dislocation  diminishes  upward ; 
the  thin  beds  break  less  and  bend  more,  until  finally  the  verti- 


FIG.  18. 


The  Jumbo,  No.  3,  Vein  Faulted  by  a  Cross-vein. 

cal  displacement  fades  out  in  horizontal  shifting.     The  latter  is 
clearly  evidenced  by  the  minute  multiple    step-faulting  of  a 


THE   ENTERPRISE    MINE,   RICO,    COLORADO. 
FIG.  19. 


39 


SANDSTONE: 


~  —  j  BLACK  SHALE 

•        ~* 

rX-^j  LI.ME  SHALE 

Disappearance  of  a  Fault. 


LIMESTONE 


40  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

quartz-seam  in  the  shale,  near  the  roof  of  the  cross-cut,  which 

FIG.  20. 


tf3 LIMES  r°NE       £S3  SANDSTONE       ggg)  SHALY-SANDSTONE  CLAY 

Disappearance  of  a  Fault. 

indicates  that  the  flexibility  o±  the  shale  enabled  it  to  resist 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  41 

fracturing  by  dissipating  the  force  of  the  vertical  movement  in 
a  sliding  of  the  laminae  over  one  another.  Fig.  20  conveys  the 
same  lesson.  The  three  quartz-seams  here  shown  follow  lines 
of  lessening  vertical  movement;  the  distinct  faulting  of  the 
beds  in  the  lower  part  of  the  section  dwindling  until  in  the 
upper  portion  only  a  slight  distortion  of  the  country  is  to  be 
discerned.  These  examples  illustrate  how  large  faults  may 
gradually  disappear,  and  suggests  why  the  vein-systems  of 
Newman  hill  terminate  in  their  approach  to  the  horizon  known 
as  the  "  contact." 

Fio.  21. 


j  LIMESTONE     {.ZHTJ  SHALE          [         (QUARTZ 


rv   SANDSTONE          ^ 

Faulting  of  Cross-vein  along  Bedding-plane. 

The  cross-veins  are  themselves  displaced  in  some  instances 
by  slight  later  movements  which  have  taken  place  along  the 
bedding-planes  of  the  country,  such  as  indicated  in  Fig.  21, 
where  a  small  south-dipping  cross-vein  is  thrown  5  inches  along 
the  parting  between  beds  of  limestone  and  sandstone. 

The  dislocation  of  the  ore-bearing  veins  by  the  cross-veins 
necessitates  the  employment  of  scientific  methods  in  mining. 
The  mine-workings  of  Newman  hill  are  needlessly  tortuous  and 
complex,  because  most  of  them  have  been  directed  by  men  blind 
to  the  indications  of  geological  structure.  The  expensive  results 
of  a  bewilderment  due  to  this  cause  are  well  illustrated  in  the 
case  of  the  Hiawatha  vein,  between  raises  No.  9  and  No.  11  on 
the  main  level.  This  particular  instance  is  quoted  because  it 
appears  in  Mr.  J.  B.  Farish's  paper  on  Newman  hill.*  His 

*  Proceedings  of  the  Colorado  Scientific  Society,  vol.  iv.,  p.  159. 


42 


THE  ENTERPRISE  MINE,  RICO,  COLORADO. 


drawing  is  here  represented  (in  Fig.  22),  together  with  another 
(Fig.  23)  based  on  a  very  close  sifting  of  the  evidence,  accom- 
panied by  a  careful  survey. 

Referring  to  Fig  22,  I  quote  Mr.  Farish's  description : 

"It  illustrates  the  occurrence  of  a  fault  in  the  Enterprise  vein  and  the  deflec- 
tion of  the  Hiawatha  vein  by  the  same  cross-fissure.  The  break  in  the  Enter- 
prise vein  is  seen  to  be  sharp,  while  the  Hiawatha  vein  is  not  faulted,  but  makes 
along  the  cross-vein  for  nearly  100  feet  before  emerging  from  its  walls  and  resum- 
ing the  original  course." 

The  vein  called  the  Enterprise  in  the  above  description  is 
not  the  Enterprise,  but  the  Songbird.     The  former  vein  has 

FIG.  22. 


Mr.  Farish's  Drawing  of  the  Hiawatha  Vein. 

never  been  found  in  this  particular  part  of  the  mine,  because  it 
breaks  up  into  unimportant  stringers  and  is  not  definitely  re- 
cognized until  nearly  400  feet  further  north.  The  Enterprise 
dips  east  slightly,  the  Songbird  dips  west  flatly.  In  their  strike 
northward  the  two  veins  unite. 

The  cross-vein  faults  both.  If  Fig.  22  were  correct  the  for- 
mation of  the  Hiawatha  would  be  later  than  that  of  the  cross- 
vein,  and  the  latter  must  be  later  than  that  of  the  so-called 
Enterprise  vein,  and  the  ore-bearing  veins  would  not  be  of  con- 
temporaneous origin.  Such,  however,  are  not  the  facts. 

The  cross-vein  strikes  the  Songbird  almost  at  right  angles 
and  throws  it  to  the  right.  When  it  meets  the  Hiawatha,  it 
throws  that  vein  to  the  left.  The  Hiawatha  and  Songbird  dip 
in  opposite  directions.  Both  faultings  are  in  accord  with 
Carnall  and  Schmidt's  rule.* 

*    In  Fault-Rules,  by  Francis  T.  Freeland,  Trans. ,  xxi.,  499. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


43 


The  representation  (in  Fig.  22)  of  the  Hiawatha  as  following 
the  cross-vein  is,  in  my  judgment,  incorrect;  the  error  having 
been  made  by  mistaking  the  "  drag "  for  ore  in  place.  The 
same  error  is  repeated  in  another  drawing  (Fig.  24)  by  Mr. 

FIG.  23. 


U9H 


The  Faulting  of  the  Hiawatha  and  Songbird  Veins  by  a  Cross-vein. 

Farish,*  which  Professor  Kemp  has  perpetuated  in  his  treatise 
on  ore-deposits. f  The  value  of  the  latter  as  a  book  of  refer- 
ence makes  it  imperative  that  the  mistake  should  be  pointed  out. 

*  Pages  158  and  159  of  the  paper  cited. 

f  The  Ore-Deposits  of  the  United  States,  by  James  F.  Kemp,  p.  20. 


44  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

Mr.  Farish  says  that  the  occurrence  represented  by  him  in 
Fig.  24  is  an  instance  of  the  "  bend  of  a  vertical  pay-vein  as  it 
approaches  an  intersecting  cross-vein,"  and  also,  that  "the 
Jumbo  vein,  as  it  approaches  and  departs  from  the  cross-fissure 
is  considerably  disintegrated,  the  numerous  seams  and  stringers 
striking  diagonally  through  the  cross-veins."  Professor  Kemp 
uses  this  drawing  to  exemplify  the  faulting  of  one  vein  by  an- 
other. Mr.  Farish's  description  would  make  it  appear  that  the 
cross-vein  existed  prior  to  the  Jumbo  vein,  and  that  the  latter 
was  bent  by  the  former,  which  it  traversed  in  seams  and 
stringers.  Yet  the  drawing,  even  as  it  is,  represents  no  fault, 
but  merely  the  bending  of  one  vein  by  another,  of  possibly 
contemporaneous  origin. 

The  real  conditions  are  represented  in  Fig.  26,  which  shows 

FIG.  24. 


Mr.  Farish's  Drawing  of  the  Jumbo  and  a  Cross-vein. 

how  the  cross- vein  faulting  the  Jumbo  carries  shattered  frag- 
ments of  the  latter  between  its  two  dislocated  parts.  The  con- 
fusion caused  by  Mr.  Farish's  attempt  to  distinguish  between 
cross-veins  that  fault  pay-veins,  of  necessarily  older  origin,  and 
cross-veins  followed  by  pay-veins,  of  consequently  later  forma- 
tion, is  due,  I  think,  to  a  failure  to  recognize  a  very  simple 
feature  of  vein-faulting.  I  refer  to  those  fragments  of  the  ore 
of  the  older  vein  which  have  been  broken  off'  by  the  fault- 
fissure  and  are  found  scattered  amid  the  newer  filling  of  the 
latter  along  that  part  of  its  course  which  lies  between  the  two 
disrupted  portions  of  the  older  vein.  This  is  the  "  drag," 
which  is  so  valuable  an  aid  in  mining,  because  it  enables  the 
miner  to  trace  the  direction  of  the  throw. 

The  faulting  of  the  "  verticals  "  by  cross-veins  is  a  prominent 
feature  in  the  Enterprise  mine.  When  half  a  dozen  drifts  were 
running  on  the  several  pay-veins  a  fault  was  encountered  about 
once  per  month.  In  other  words,  the  distance  between  the 
cross-veins  averaged  from  65  to  100  feet.  Failure  to  apply  the 


D 


I   50     i 

m    C      S 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  45 

elementary  rules  of  faulting  and  to  make  such  observations, 
measurements  and  calculations  as  would  serve  to  identify  a 
cross-vein  as  it  passed  through  the  series  of  nearly  parallel  ver- 
ticals, has  caused  much  unnecessary  expenditure  on  Newman 
hill.  More  broken  ends  of  faulted-veins  were  happened  upon 
by  accident  in  "  drifting  "  than  were  discovered  by  intelligent 
search.  The  practical  importance  in  mining  of  the  study  and 
interpretation  of  geological  structure  is  forcibly  emphasized  by 
this  record  of  experience. 

Out  of  over  two  hundred  instances  of  faulting  noted  during 
my  twelve  months'  direction  of  the  Enterprise  mine,  I  detected 
only  one  (and  that  an  uncertain)  exception  to  Carnall  and 
Schmidt's  rule,  which  is  stated  by  Mr.  Freeland  as  follows  :* 

' '  If  the  fault  be  encountered  on  its  hanging-wall  side,  after  breaking  through  it, 
prospect  toward  the  hanging-wall  side  of  the  vein  ;  on  the  contrary,  if  from  the 
foot- wall  side,  then  prospect  toward  the  foot- wall  side  of  the  vein." 

"  This  rule,  as  Mr.  Freeland  says,  "  applies  only  to  normal 
faults,  and  is,  in  addition,  subject  to  an  important  exception."f 
I  do  not  cite  it  as  the  statement  of  a  universal  law.  In  other 
districts  other  rules  may  be  found  applicable.  NOT  is  it  neces- 
sarily to  be  expected  that  in  any  one  district  a  single  rule  only 
will  obtain.  But  if  in  a  given  locality  the  prevalence  of  a 
given  fault-rule  (expressing  the  habit  of  the  veins  in  that  local- 
ity) can  be  demonstrated,  a  working-hypothesis  of  immense 
value  is  thereby  furnished  to  the  miner.  My  remarks  in  this 
connection  are  to  be  taken,  therefore,  as  applicable  only  to  the 
district  here  under  consideration,  or  to  other  districts  in  which 
similar  conditions  may  be  determined  by  experience. 

When  a  cross-vein  intersects  a  pay-vein  at  an  acute  angle  it 
is  practicable  to  follow  the  trail  of  the  latter,  as  evidenced  by 
the  scattered  fragments  constituting  the  "  drag."  When,  how- 
ever the  faulting  occurs  at  a  large  angle  there  is  less  evidence 
of  the  direction  of  the  throw,  and  a  level  driven  on  the  cross- 

*  Trans.,  xxi.,  499. 

f  "  Normal  faults  "  are  those  in  which  the  rock  forming  the  hanging-wall  of  the 
fault  has  moved  downward  along  the  foot-wall  of  the  fault.  The  exception  to 
Carnall  and  Schmidt's  rule  mentioned  by  Mr.  Freeland  in  the  above  quotation  is 
that  of  an  obtuse  fault-angle.  The  rule  might  be  so  stated  that  this  would  be  no 
exception,  as  the  case  is  simply  one  of  an  acute-angled  fault,  approached  from  the 
other  side. 


46 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


vein  until  it  meets  the  other  portion  of  the  disrupted  vertical 
would  involve  turns  too  sharp  for  subsequent  use  in  tramming. 
It  might  thus  be  necessary,  after  finding  the  continuation  of  the 
pay- vein,  to  run  a  new  piece  of  level  for  practical  mining  pur- 
poses. But  if  the  direction  of  the  throw  be  known  from  pre- 

FIG.  26. 


Faulting  of  the  Jumbo  by  a  Cross-vein. 

vious  experience,  the  heading  can  be  so  turned  as  to  strike  the 
vein  beyond  its  dislocation  by  a  course  of  minimum  deflection, 
making  a  practicable  mine-level. 

When  a  cross-vein  meets  a  vertical  at  a  very  small  angle  a 


Fio.  27. 


Outline  of  Mine  Levels 


Ore  Vein 


Cross  Vein 


AMERICAN  BANK  NOTE  CO.N.Y.  Y 


A  Vein  Faulted  almost  at  Eight  Angles. 


A  Vein  Faulted  at  a  Small  Angle. 


slight  throw,  as  measured  at  right  angles  to  the  strike,  becomes 
sufficient  to  produce  a  wide  separation  between  the  broken 
ends  as  measured  along  the  course  of  the  pay-vein.  In  such 
cases  it  is  easy  for  the  unobservant  miner  to  be  misled  by  the 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


47 


unapparent  deviation  in  his  level  and  to  mistake  a  cross-vein 
carrying  fragments  of  lode-matter  for  the  pay-vein  itself.  (See 
the  diagrammatic  sketches  in  Figs.  27  and  28.) 


29. 


|£:-iiji£:-:3  SANDSTONE  F^^tZ^y 


LIMESTONE 


DISORDERED  LIME 


SOFT  CRUSHED  L'ME 


Cross-vein  as  seen  in  the  Breast  of  a  Drift  on  Jumbo  No.  2. 

The  rhodochrosite  is  a  great  aid  in  tracing  the  ore-bearing 
veins  because  its  bright  color  renders  it  readily  distinguishable 
amid  the  white  quartz  or  the  dark  shattered  country  of  the 
cross-veins,  and  its  absence  distinguishes  the  latter  just  as  its 
presence  characterizes  the  pay-veins. 


48 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


Figs.  29,  30  and  31  illustrate  the  behavior  of  two  cross-veins, 
encountered  in  following  the  Jumbo  "No.  2  lode.  Fig.  29  shows 
the  cross-vein  in  the  breast  of  the  level.  It  consists  of  2  to  3 


SANDSTONE  A 


LIMESTONE 


1  BLACK 
=.  CRUSH  ED 

L|ME 


SANDSTONE  B 


SELVAGE 
RHODOCHROSITE 


Two  Cross-veins  Approaching  Each  Other. 


feet  of  crushed  country,  enclosing  stringers  of  quartz.  There 
is  a  fault,  but  its  extent  cannot  be  determined.  The  wedge  of 
sandstone  observable  near  the  floor  of  the  drift  marks  the  be- 


THE  ENTERPRISE  MINE,  RICO,  COLORADO. 


49 


'••.•Iv:"".:  :'•:  SANDSTONE 


BLACK  CLAY 


jr^X-    LIMESTONE 


VEIN 


(Igp^a  BLACK  LIME 
SHALE 


f  V. '»V.if  - «'.\C  R  U  S  H  E  D 
I3S?-:<^S3  QUARTZ 


^SSSSA  SELVAGE 

A  Vertical  and  a  Cross-vein  Intersecting. 


f-rx        CRUSHED  SANDSTONE 

'• 


50  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

E  FIG.  32. 


._    •«*»^.*--i.    *  -^•.<-.:-.-- 


t.ME-SHALE  BLACK  SHALL 


Ojfyl CRUSHED  ROCK 
0  1 


LAMINATED 
LIMESTONE 


Scale  of  Feet 

Porphyrite  Dike  at  the  Contact. 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


51 


ginnings  of  a  separation  which  Fig.  30  shows  to  be  the  depar- 
ture of  one   of  two   consolidated   cross-veins.       One   of  these 


FIG.  33. 


BLACK  SHALE 


HARD  SANDSTONE 


r*     CROSS  VEIN 


BREAST  OF  CROSSCUT  WEST  OF   ENTERPRISE  LEVEL,  APRIL  10TH.  1894 

began  at  this  time  to  exhibit  pieces  of  rhodochrosite,  which 
soon  afterwards  led  to  the  finding  of  the  vein.  Fig.  31  illus- 
trates another  cross-vein.  The  structure  is  complicated.  The 
narrow  seam,  A  A,  and  its  enclosing  vein-filling  have  been 


52  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

FJG.   34. 


East       . 
Scale, '%  in.=l  ft. 


I  SANDSTONE  |  ~^_Tr'  \  LIMESTONE 

RHODOCHROSITE  f       ")  QUARTZ  ffiSwl  BLENDE 


AMERICAN  BANK  NOTE  ( 


"Z^JLIME  SHALE 

| CRUSHED  ROCK 


KITCHEN  VEIN 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  53 

faulted  along  a  bedding  plane,  B  B,  and  subsequently  a  move- 
ment along  the  hanging-wall  of  the  cross-vein  has  led  to  another 
dislocation,  a  down-throw  of  the  country  and  a  distortion  of 
the  former  line  of  movement.  It  is  interesting  to  note  that  the 
secondary  companion  cross-vein  thus  formed  consists  of  crushed 
sandstone,  D,  in  the  upper  part  of  the  section,  and  of  black 
lime,  E,  which  has  been  crushed  into  clay,  in  the  lower  part. 
This  change  corresponds  with  the  alternation  of  rock  in  the 
enclosing  country. 

Fig.  33  illustrates  a  fine  example  of  double  faulting.  The 
steep  cross-vein  has  caused  a  displacement  of  a  little  over  2 
feet,  which  is  very  clearly  marked  by  the  dark  band  of  sand- 
stone. Subsequently  a  shifting  along  bedding-plane  has  faulted 
the  cross-vein  about  20  inches. 

Fig.  34  is  a  section  of  the  Kitchen-vein,  as  seen  in  the  face  of 
a  south  drift.  This  vein  dips  westward.  The  example  is  of 
value  because  of  the  inclusion  of  fragments  of  country-rock. 
Of  these,  some  (CC)  are  sandstone  and  others  (DD)  lime. 
Their  distribution  corresponds  with  that  of  the  rocks  on  the 
foot-wall,  and  suggests  that  they  were  torn  off  the  enclosing 
country.  The  mineralization  of  the  rock  and  the  substitution 
of  ore  is  suggested  by  the  fact  that  each  of  these  included  pieces 
has  a  well-marked  rim  of  rhodochrosite.  On  the  hanging-wall 
there  is  no  parting  from  the  country ;  on  the  foot>wall  the  ore 
is  readily  detached,  because  of  the  existence  of  a  continuous 
selvage  of  black  mud.  Ribboning,  due  to  alternations  of  quartz, 
rhodochrosite  and  blende,  is  well  marked  in  the  upper  hanging- 
wall  portion  of  the  section.  This  vein  follows  a  fault-fracture, 
the  throw  of  which  exceeds  5  feet,  an  amount  unusual  to  the 
pay-veins  of  the  Enterprise  mine. 

The  occurrence  of  dikes  and  tongues  of  porphyrite  has  been 
noted  incidentally.  The  deep  shafts  and  bore-holes  have  en- 
countered large  thicknesses  of  it  among  the  sedimentary  rocks 
underlying  the  horizon  of  the  existing  mine-workings.  The 
sedimentaries  have  been  found  hardened  and  otherwise  aft'ected 
in  the  vicinity  of  the  eruptive  rock,  so  that  sandstone  appears 
as  quartzite  and  limestone  is  converted  into  marble.  What  the 
real  character  of  this  body  of  porphyrite  may  be  cannot  be  de- 
termined from  the  evidence  at  my  disposal.  The  more  general 
observations  of  the  gentlemen  of  the  Geological  Survey  will 


54 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


doubtless  throw  much  light  on  the  matter.  To  the  mining  en- 
gineer one  fact  stands  out  very  prominently,  that  whether  in 
their  strike  northward,  approaching  the  porphyrite  of  Silver 

Fig.  35. 


Quartz 


Limestone 


Crushed  Rock 


A  TYPICAL  CROSSVEIN. 

creek,  or  in  their  extension  downward,  toward  the  lower-lying 
body  of  that  rock,  the  veins  become  impoverished  of  pay-ore. 
In  view  of  the  general  recognition  of  the  beneficent  association 
of  veins  with  eruptive  rocks,  this  is  very  instructive.  The  ex- 
planation suggests  itself  that  though  the  shattering  of  the 
country  accompanying  the  intrusion  of  the  porphyrite  aided 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  55 

vein-formation,  because  of  the  passageways  thereby  developed 
for  the  circulation  of  underground  waters,  yet  at  the  same 
time  the  immediate  neighborhood  of  hot  masses  of  eruptive 
material  did  not  favor  the  precipitation  of  ore,  and  that  the 
best  deposition  took  place  at  such  a  distance  as  permitted  the 
cooling  of  the  waters  and  the  consequent  laying  down  of  the 
metals  they  carried  in  solution. 

The  veins  penetrate  the  porphyry.  The  contact  in  many 
places  carries  fragments  of  porphyry.  These  facts  prove,  as 
would  be  readily  surmised,  that  vein-formation  succeeded  the 
intrusion  of  the  porphyry. 

In  the  stopes  irregular  tongues  of  porphyrite  were  occasion- 
ally observable.  As  they  only  followed  the  vein  for  a  short 
distance  in  its  strike  and  dip,  it  was  not  possible  to  find  out 
much  about  them.  Such  occurrences  are  seen  in  Figs.  5,  15 
and  16.  Fig.  32  is  a  drawing,  which  I  made  with  particular 
care,  showing  how  a  dike  is  shattered  at  the  contact.  The 
porphyrite  is  14  inches  wide.  Along  the  parting  AB  it  is 
fractured,  and  a  clay  selvage  across  it  suggests  later  movement 
(in  the  direction  of  the  strike,  so  that  the  cross-section  does 
not  show  it).  At  the  level  of  CD  the  dike  is  smashed  to  pieces. 
A  disturbance  along  the  contact  has  shifted  some,  of  the  frag- 
ments. The  regular  passage  of  the  dike  upward  has  been  in- 
terfered with  at  the  contact,  and,  previous  to  the  shattering,  it 
seems  to  have  divided  into  branches,  of  which  three  (termina- 
ting in  the  sketch  at  E,  F  and  G)  still  survive.  The  contact  itself, 
here  marked  by  a  thickness  of  nearly  5  feet  of  crushed  shale, 
crushed  sandstone  and  lime,  contains  numerous  fragments  of 
porphyrite.  Apart  from  its  bearing  on  the  origin  of  the  dikes, 
this  drawing  illustrates  how  the  contact  barred  the  progress 
upward  of  fissuring  of  every  kind. 

VI. — THE  CONTACT. 

As  the  ore-bearing  veins  are  followed  by  the  mine-workings* 
they  are  found  to  split  up,  weaken  and  become  impoverished 


*  Entrance  to  the  mines  is  made  through  long  adits  which  aim  to  cut  the  veins 
at  a  depth  of  50  to  100  feet  below  the  contact.  Hence  the  regular  vein -structure 
is  first  seen,  and  the  other  complications  come  under  notice  as  the  stopes  and  raises 
are  ascended.  This  order  has  been  observed  in  describing  them  here. 


56 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


at  a  certain  horizon,  lying  from  5  to  20  feet  below  a  zone  of 
crushed  rock,  in  which  are  enclosed  ore-bodies  richer  than  those 
of  the  veins  themselves.  It  is  rarely  that  even  diminished  seams 
of  ore  survive  so  as  to  connect  with  the  ore  on  this  contact. 
Ordinarily  the  highest  stope  on  the  "  vertical "  is  separated  from 
the  nearest  stope  on  the  "  contact "  by  a  few  feet  of  black  shale 

Fig.  36. 


Black  finely  laminated  Shale 


Ore 


Limestone 


JUMBO  No.  2.  VEIN  AT  THE  CONTACT 

and  lime,  containing,  at  best,  only  scattered  remnants  of  the 
vein.  Figs.  36  and  37  give  simple  examples.  Occasional  sec- 
tions show  no  connection  between  the  vertical  and  the  contact 
overhead.  Such  small  quartz  or  rhodochrosite  threads  as  do 
occur  have  no  continuity. 

The  cross-veins  behave  in  relation  to  this  contact  in  a  man- 
ner very  similar  to  the  pay-veins.  Since  they  are  barren  of  ore, 
there  are  no  workings  which  folloAv  the  cross-veins  in  their 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


57 


immediate  approach  to  the  contact,  but  there  is  scattered  evi- 
dence* sufficient  to  confirm  this  statement.  There  is,  how- 
ever, a  notable  difference  between  the  behavior  of  the  two 
systems  of  vein  fissuring  when  they  reach  the  contact.  The 
economically  important  observation  has  been  made  that  the 
cross-veins  are  less  regularly  topped  by  ore-bodies  along  the 

Fig.  37. 

• _  I ' __       ~— -  Black  Shale 


Sandstone 


<?'>'* 


«»" »  '.» :  *   •    v  vf  "  •*  ~ *  '•  &  •  •     '  '*  • 

il?&;&*$&$££ 

,^^^^/^m^wM. 

71+i'l'^^^t^, 

-  ,-r  H^'-  ^' 

-    -vl -' 


^I-X^ 


Brecclated  Lime 


Ore 


Gray  Limestone 


Black  Lime 


A    TYPICAL    CONTACT 


contact  ;  but,  on  the  other  hand,  such  ore-bodies  as  have  been 
found  over  cross-veins  have  been  usually  larger  and  certainly 
richer  than  those  apparently  related  to  underlying  verticals. 

The  dislocating  influence  of  the  pay-veins  appears  to  die  out 
in  its  approach  to  the  contaekzone,  so  that  the  latter  undergoes 
a  mere  undulation  or  roll  along  its  bedding-planes.  At  the 
same  time  the  pay-veins  become  unrecognizable,  even  as  minute 


*  Obtained  from  stopes  under  the  contact,  in  places  where  a  cross-vein  happens 
to  cut  a  vertical  as  it  is  dying  out. 


58  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

seams  or  partings,  in  the  rocks  above  the  contact.  In  the  case 
of  the  cross-veins,  however,  a  more  serious  disturbance  of  the 
contact-zone  is  indicated  by  violent  bends  and  occasional  step- 
faults.  The  cross-vein  itself,  though  it  does  not  reappear  above 
the  contact  as  a  strong  quartz-seam,  is  yet  represented  by  a 
well-developed  division  in  the  country  accompanied  by  selvage. 
Fig.  38  represents  a  section  along  the  contact,  where  it  is  dis- 
located by  a  cross- vein.  The  latter,  A  B,  splits  at  the  contact, 
both  branches,  B  C  and  B  D,  following  fault-lines.  The  ore  of 
the  contact,  which  is  here  related  to  the  Jumbo  No.  2  vein, 
consists  of  low-grade  quartz  from  a  couple  of  inches  to  more 
than  a  foot  in  thickness,  overlain  by  a  thin  bed  of  black  shale 
and  underlain  by  limestone.  Above  the  shale  is  a  bed  of  brec- 
cia, about  2  feet  thick,  composed  of  fragments  of  limestone, 
with  occasional  pieces  of  porphyrite  and  shale.  It  will  be 
noticed  how  the  quartz-ore  follows  the  bedding  and  the  con- 
necting fault-fissures. 

When  the  contact  was  first  penetrated  by  the  shafts  sunk 
from  the  surface  (through  the  drift  covering  the  sandstones  and 
limestones  which  contain  the  ore-deposits)  it  was  supposed  to  be 
a  "  flat  vein."  When  later  developments  proved  it  to  conform  to 
the  bedding  of  the  country,  it  became  recognized  as  distinct 
from  the  other  vein-systems  which  cut  the  bedding  at  a  right 
angle.  Hence  grew  the  idea  that  there  existed  here  a  lime- 
stone-shale contact  similar  to  that  of  Aspen  and  resembling 
the  ore-bearing  zones  in  the  Carboniferous  blue  lime  of  Lead- 
ville.  More  extensive  exploration  dissipated  the  hope  of  a  con- 
tinuous ore-bed,  but  although  the  occurrence  of  harrow  chan- 
nels of  rich  mineral,  ramifying  through  the  brecciated  beds  of 
the  contact,  was  demonstrated,  it  was  not  at  first  seen  how 
clearly  these  corresponded  with  the  strike  of  the  two  vein- 
systems,  the  upward  course  of  which  was  terminated  by  the 
contact.  The  recognition  of  this  relationship  was  a  key  un- 
ravelling many  perplexities,  and  a  light  to  the  intelligent  ex- 
ploration of  a  territory  of  complex  geological  structure. 

The  contact  is  not,  as  the  term  might  imply,  a  continuous 
plane  of  division  between  two  rock  formations,  nor  does  it  mark 
the  parting  between  the  two  adjoining  beds  of  ore  formation. 
The  accounts  which  have  been  given  of  a  "  coiitac1>limestoiie," 
overlain  by  a  "  drab  shale  "  and  underlain  by  a  "  finely  lamina- 


THE  ENTERPRISE  MINE,  RICO,  COLORADO. 


59 


•;^y?:^?y* 

Slti 


60 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


ted  shale,"*  may  describe  certain  sections  of  this  ore-bearing 
horizon,  but  they  do  not  characterize  it  as  a  whole,  and  they 


Fig.  3«J. 


THE  CONTACT  ABOVE  THE  ENTERPRISE  VEIN 


Lime  Breccia 


Lime  Breccia 


Blocky  Lime 


Limestone 


give  a  misleading  idea  of  its  real  nature.     In  the  three  sections 
already  given,  in  Figs.  36,  37  and  38,  the  contact  is  found  re- 


*  J.  B.  Farish,  "On  the  Ore-Deposits  of  Newman  Hill."     Proceedings  Colorado 
Scientific  Society,  vol.  iv.,  and  James  F.  Kemp,  Ore-Deposits  of  the  United  /States, 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


61 


spectively  in  a  crystalline  lime,  overlain  by  black  shale  and  un- 
derlain by  sandstone ;  in  a  lime-breccia,  underlain  by  sandstone 
and  underlain  by  a  gray  limestone ;  and  in  the  third  instance 


Fig.  40. 


Sandstone 


Black  Selvage 
FACE  OF  A  STOPE  ON  THE  CONTACT 

in  a  mass  ot  crushed  quartzose  lime,  covered  by  black  shale 
and  overlying  a  blocky  limestone.  Additional  sections  are  now 
given  in  Figs.  39,  40  and  41.  In  the  first  of  these  we  see  the 
stringers  thrown  out  by  the  Enterprise  vein  as  it  nears  the  con- 
tact, which  in  this  case  consists  of  brecciated  lime,  enclosing  a 
low-grade  quartz  ore.  In  Fig.  41  another  similar  example  is 


62 


THE  ENTERPRISE  MINE,  RICO,  COLORADO. 


given.  In  Fig:  40  the  contact-ore  lies  at  the  base  of  a  bed  of 
gypsum,  which  in  turn  overlies  limestone,  penetrated  by  string- 
ers, which  come  from  the  Jumbo  No.  3  vein  below. 

The  ore  of  the  contact  cannot  be  said  to  be  confined  to  any 


particular  encasement;  but  one  may  venture  the  generalization 
that  it  is  to  be  sought  for  in  a  layer  of  crushed  rock,  which 
occurs  along  a  certain  horizon  marked  by  a  thinly-bedded  series 
of  black  limestones  and  shales.  The  parts  of  the  contact  ex- 
plored during  my  period  of  management  were  very  frequently 
characterized  by  a  distinct  breccia  made  up  principally,  but  not 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


solely,  of  lime-fragments.  Pieces  of  shale  and  sandstone  were 
recognizable  as  derived  from  adjacent  beds ;  and  fragments  of 
porphyrite  were  traceable  to  neighboring  intrusions  of  that  rock. 
The  contact  above  the  Jumbo  "No.  2  frequently  consisted  of 
compact,  pulverulent  lime,  graduating  into  breccia  overhead  and 
underlain  by  blocky  lime ;  that  above  the  Enterprise  was  often 
breccia,  shading  off  into  blocky  lime  overhead,  and  underlain 

Fig.  42. 

<7        .    •  •      . 

•   ff  **    -  i^3  "Q  -/     jy   -f70        *--    •          ° 


:i,     Breccia;  b,     Crushed  Lime  and  Quartz;  c,       Lime;  d,      Laminated  Lime; 

e,        Sandstone;  /,       Blocky  Lime. 

A  BARREN  CONTACT. 

by  black  shale ;  while  the  ore  of  the  Jumbo  ~No.  3  contact  was 
found  between  a  powdery  brown  lime  and  a  thin  bed  of  black 
shale.  The  variability  of  the  stratigraphical  position  of  the  ore, 
thus  emphasized,  is  due  to  the  non-persistence  of  individual 
beds. 

Except  when  it  tops  the  veins,  the  contact  is  barren.  Fig. 
42  illustrates  the  face  of  a  cross-drift  on  the  contact  where  no 
veins  have  enriched  it.  In  Fig.  43  an  intrusion  of  porphyrite 
is  shown.  The  pulverulent  lime  indicates  crushing,  probably 
accompanying  the  invasion  of  the  porphyrite. 

The  crystalline  limestone  of  many  sections  is  doubtless  breccia 
consolidated  by  pressure  and  cemented  by  the  underground 


64 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


waters  which  have  lined  the  cavities  with  crystals  of  calcite. 
The  gypsum  bed  to  be  seen  in  the  southwestern  part  of  the 

Fig.  43. 


f-  -j-  -j-       Porphyrite 


Black  Shale 


Brown  Purverulent  Lime 


Ore  and  Quartz 


SECTION  ABOVE  THE  JUMBO  No.  3. 


Limt 


mine  affords  a  parallel  instance.  A  section  is  given  in  Fig. 
40.  The  vein  whose  shattered  termination  is  to  be  seen  below 
the  ore  of  the  contact  is  the  Jumbo  ~No.  3.  The  gypsum  thins 


THE    ENTERPRISE    MINE,    RICO,    COLORADO.  65 

out  and  is  a  local  occurrence  having  a  maximum  thickness  of 
15  feet.  Its  wavy,  compact  texture  suggests  an  origin  by  a  sul- 
phatization  of  lime-breccia  through  the  agency  of  solutions  com- 
ing from  neighboring  ore-bearing  measures.* 

The  foregoing  general  description  will  assist  the  reader's  un- 
derstanding of  Fig.  C,  which  represents  a  part  of  the  workings 
on  the  main  (also  called  the  Enterprise)  level,  98  feet  above  the 
Group  tunnel.  It  covers  an  area  about  1800  feet  long  by  350 
feet  wide,  and  was  chosen  for  especial  examination  and  study 
because  the  developments  are  more  complete  than  in  any  other 
part  of  Newman  hill,  while  at  the  same  time  they  present  fea- 
tures sufficiently  typical  of  the  ore-occurrence  over  the  whole 
territory  covered  by  the  mine  maps. 

The  levels  are  seen  to  follow  three  veins,  the  Enterprise,  Song- 
bird and  Hiawatha,  the  dip  of  which  is  indicated  by  the  arrows. 
Commencing  at  the  crosscut  from  the  Enterprise  shaft  the  En- 
terprise vein  is  followed  without  difficulty  as  far  as  Raise  6,f 
where  the  vein  dies  out  in  weak  stringers.  Up  to  this  point 
the  stopes  extended  to  the  contact;  but  northward,  stoping 
ceases  on  this  vein.  The  vein  which  the  level  followed  further 
on,  from  R8S,  was  once  considered  the  Enterprise  because  of 
imperfect  observation  of  the  facts.  So  also  the  vein  followed 
by  the  level  further  north  still,  from  R15E  to  R18E,  is  called 
the  Enterprise.  It  is  a  branch  vein,  a  subordinate  member  of 
the  series  of  many  disclosed  in  the  mine. 

There  is  too  frequent  a  tendency  in  mining  to  look  upon 
veins  as  necessarily  continuous,  and  to  make  the  nomenclature 
correspond  to  the  drifts.  In  this  case,  a  level  follows  three  dis- 
tinct veins  in  different  parts  of  its  length.  The  crosscut  be- 
tween R7JE  and  R8S  was  put  out  to  search  for  the  Enterprise 
vein  in  case  it  had  been  faulted  by  the  two  cross-veins,  G  and 
H.  It  proved  that  this  particular  vein  had  ceased ;  but  it  led 
to  the  discovery  of  the  Kitchen  lode. 

The  numerous  cross-veins  are  mapped,  and  their  dislocating 
influence  on  the  pay-veins  is  easily  discernible. 

*  A  large  body  of  gypsum  also  occurs  along  the  contact  in  the  Vestal  workings 
of  the  Rico- Aspen  mine. 

f  The  raises  are  numbered  and  initialed,  so  that  E6E  means  Kaise  No.  6  on  the 
Enterprise,  E10H,  Kaise  No.  10  on  the  Hiawatha,  etc. 

5 


66 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


Returning  to  the  crosscut  from  the  Enterprise  shaft,  we  will 
follow  the  Songbird,  which  there  appears  as  a  small  vein  having 


a  slight  easterly  dip.     Going  northward  (to  the  right),  the  level 
shows  it  to  flatten.     The  next  time  it  is  seen,  560  feet  further 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


67 


68 

north,  it  has  changed  its  dip  strongly  westward.  The  cross- 
veins,  G  and  H,  fault  it,  and  it  appears  in  the  Enterprise  drift 
at  R8S.  The  cross-vein  K  throws  it  19  feet  eastward,  and  it 
is  then  seen  at  intervals  in  cross-cuts  and  raises  until,  beyond 
B17E,  at  the  crosscut  to  the  Laura  shaft,  it  merges  with  the 
branch-vein,  sometimes  labelled  the  Enterprise.  The  Hiawatha 
is  disturbed  by  the  same  series  of  cross-veins,  and  in  one  case 
suffers  a  very  serious  dislocation,  namely,  between  R9H  and 
B11H,  as  already  described  in  the  discussion  of  Fig.  23. 

These  veins  were  followed  by  raises  and  stopes  to  the  contact 
overhead,  and  upon  the  contact  ore-bodies  were  found  having  a 
narrow  width  and  courses  corresponding  to  the  strike  not  only 
of  the  pay-veins,  but  also  of  the  cross-veins.  Thus  both  series 
of  veins,  older  and  younger,  rich  and  poor,  are  topped  by  bands 
of  ore  distributed  along  this  horizon,  so  as  to  make  a  network 
the  intricacy  of  which  for  a  long  time  obscured  its  real  charac- 
ter. The  map  exhibits  the  contact  ore-bodies  and  proves  very 
clearly  their  connection  with  the  two  series  of  veins.  The  two 
sections,  along  XY  and  PQ,  will  further  help  to  explain  this. 

Thus  it  became  evident,  after  careful  surveys  and  the  pro- 
jecting of  the  dip  of  the  veins  to  their  intersection  with  the  con- 
tact, that  no  ore  occurred  upon  that  contact  which  was  not  re- 
lated to  the  underlying  veins,  and  that  the  latter,  conversely, 
were  always  topped  by  ore,  although  that  ore  was  not  necessa- 
rily always  wide  enough  and  rich  enough  to  exploit. 

The  geological  relationship  was  abundantly  proved ;  and 
when  the  writer  prepared  this  map  by  first  putting  the  veins  as 
the  surveys  had  traced  them,  and  then  platting  the  ore-bodies 
of  the  contact  as  the  stopes  had  exposed  them,  it  was  very  re- 
markable to  discover  how  the  latter  corresponded  with  the  pro- 
jections of  the  former. 

Fig.  D  is  a  longitudinal  section  along  one  of  the  pay-veins, 
showing  how  the  ore  ceases  at  the  contact,  and  how  the  stopes 
extend  only  a  short  depth  below. 

Fig.  E  is  a  section  along  the  Group  tunnel,  affording  an  illus- 
tration of  the  series  of  pay-veins  and  their  relation  to  the  con- 
tact. 

VII. — ORIGIN  OF  THE  ORE-DEPOSITS. 
The  structure  and  composition  of  the  ore-deposits  of  New- 


THE    ENTERPRISE    MINE,    RICO,    COLORADO. 


69 


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70  THE    ENTERPRISE    MINE,    RICO,    COLORADO. 

man  hill  offer  suggestions  of  their  origin.  Reference  has 
already  been  made  to  the  slow  recognition  of  their  true  rela- 
tions which  came  in  the  wake  of  extended  mine-exploration. 
When  the  connection  between  the  flat  ore-bodies  of  the  contact 
and  those  of  the  vertical  veins  underneath  them  was  first  traced- 
there  arose  the  idea  that  the  ore  of  the  former  had  "  spilled 
over  "  into  the  latter  ;  in  other  words,  the  theory  of  descending 
solutions  was  advocated.  Such  ideas  were  expressed  by  some 
of  the  experts  who  testified  during  the  long  litigation  between 
the  Enterprise  and  Rico- Aspen  companies.  All  the  available 
evidence  on  the  subject,  however,  both  geological  and  chemical, 
is  opposed  to  this  view. 

The  rocks  enclosing  the  ore-deposits  have  undergone  suc- 
cessive rupturing,  resulting  in  the  creation  of  a  series  of  frac- 
tures which  have  served  as  water-ways  available  for  the  circu- 
lation of  mineral-bearing  solutions.  The  fact  that  the  ore-bearing 
verticals  penetrate  the  porphyry,  and  the  shattered  condition  of 
the  latter  along  the  horizon  of  the  contact,  prove  that  its  intru- 
sion among  the  sedimentary  rocks  preceded  the  formation  of 
the  ore-bearing  fissures.  The  crossings  of  the  later  systems  of 
fissuring  establish  their  relative  age.  Thus,  then,  we  have  evi- 
dence that  a  condition  of  strain  culminated  in  a  multiple  frac- 
turing of  the  Carboniferous  rocks,  and  the  formation  of  certain 
of  these  fractures  was  accompanied  pari  passu  by  the  slow  up- 
welling  of  mobile  igneous  matter  which,  when  cooled  and 
solidified,  became  the  porphyrite  of  to-day.  Outside  the  area  of 
the  mine-workings  large  faults  and  enormous  intrusions  of  por- 
phyrite did  occur,  but  within  the  region  of  ore-deposition  the 
forces  at  work  produced  a  system  of  small  multiple  fractures 
and  did  not  permit  the  invasion  of  large  masses  of  porphyry. 
These  results  are  vaguely  ascribed  to  a  condition  of  strain,  and 
the  analogy  of  other  better  known  regions  permits  us  to 
ascribe  this  strain  to  a  local  manifestation  of  that  wider  phe- 
nomenon called  the  continental  uplift,  itself  a  part  of  the  read- 
j  ustment  of  the  earth's  exterior  to  a  shrinking  interior. 

During  the  next  disturbance  of  equilibrium,  a  disturbance 
probably  due  to  the  contraction  following  upon  the  cooling  of 
the  included  masses  of  porphyrite,  a  set  of  new  fractures  was 
formed7  and  along  these  underground  waters  began  to  move. 
When  they  had  precipitated  valuable  ores  along  their  channels 


THE  ENTERPRISE  MINE,  RICO,  COLORADO.          71 

of  circulation,  later  movements  produced  a  series  of  cross-frac- 
tures which  faulted  them.  Minor  shiftings,  which  have  super- 
vened at  various  more  recent  times,  have  caused  displacements 
along  the  bedding,  affecting  hoth  of  the  older  vein-systems. 

The  contact-zone  has  been  the  victim  of  all  these  disturbances. 
This  is  to  be  ascribed  directly  to  its  structure.  A  thickness  of 
closely-laminated  shales  is  laid  upon  blocky  limestones  and 
sandstones.  To  the  formation  of  a  fracture  the  latter  rocks 
would  offer  no  particular  obstacle,  because  of  their  homogeneity ; 
but  the  upward  extension  of  a  fracture  would  be  impeded,  if 
not  stopped,  by  meeting  a  series  of  beds  which,  on  account  of 
their  laminated  structure,  are  easy  to  bend,  but  hard  to  break. 
There  is  nothing  fanciful  in  this  reasoning.  The  section  given 
in  Fig.  19  affords  an  illustration  exactly  in  point.  Thus,  it 
seems  to  me,  the  structure  of  the  rocks  of  the  horizon  now 
known  as  the  "  contact,"  was  the  immediate  cause  of  the  re- 
peated shattering  which  that  horizon  underwent ;  it  was  the  fac- 
tor which  stopped  the  upward  extension  of  the  vein  fractures 
and  produced  the  consequent  limitation  to  the  circulation  of  those 
mineral  solutions  which  were  the  immediate  agents  of  ore-de- 
position. Thus  is  explained  the  concentration  of  large  masses 
of  ore  along  this  zone,  because  it  became  a  dam,  checking  the 
circulation  in  an  upward  direction.  The  fractures  now  followed 
by  the  pay-veins  were  unable  to  break  through  the  shales  above 
the  contact,  and  though  the  later  cross- veins  were  stronger, 
they  too  were  stopped  by  the  elasticity  of  these  closely-laminated 
beds. 

In  each  case,  therefore,  the  force  of  vertical  fracturing  was 
diverted  into  a  horizontal  displacement  which  soon  made  the 
zone  under  the  shales  a  mass  of  shattered  rock,  peculiarly 
adapted  to  become  the  place  of  ore-deposition. 

The  ore  is  confined  to  the  pay-veins  for  a  depth  of  100  to  175 
feet  below  the  contact.  It  does  not  occur  in  the  cross-veins,  but 
is  found  in  the  contact  immediately  above  them,  as  above  the 
pay-veins.  This  distribution  cannot  be  satisfactorily  explained 
with  positive  certainty.  There  are  so  many  conditions  deter- 
mining the  character  of  an  ore-deposit,  and  ordinary  mine- 
exploration,  being  a  commercial  enterprise  and  not  a  scientific 
inquiry,  reveals  so  few  of  them,  that  the  geologist,  though  aided 
by  the  chemist,  is  often  at  a  loss.  Yet,  in  this  case,  the  avail- 


72          THE  ENTERPRISE  MINE,  RICO,  COLORADO. 

able  evidence,  though  in  many  ways  inconclusive,  is  highly 
suggestive. 

The  ore-bodies  of  the  contact  apparently  owe  their  existence 
to  a  combination  of  chemical  and  physical  conditions.  The 
ending  of  the  vein-fractures  at  the  contact-horizon  put  a  stop  to' 
the  upward  flow  of  the  metal-bearing  solutions,  and  caused  them 
to  permeate  the  shattered  rock  and  distribute  themselves  along 
the  strike  of  the  veins  which  had  been  their  passage-way.  At 
the  contact  they  found  the  chemical  precipitant  which  com- 
pelled the  dissolved  metals  to  separate  out  as  aggregates  of  ore. 
That  precipitant  was  probably  the  graphite  of  the  black  shales, 
as  is  indicated  by  actual  experiments  presently  to  be  described. 

The  non-persistence  of  the  ore  of  the  pay-veins  below  a  cer- 
tain distance  from  the  contact  is  apparently  connected  with  the 
circumstance  that  the  sedimentary  rocks  immediately  below  the 
contact  are  black,  by  reason  of  the  carbonaceous  residues  of  the 
vegetation  imbedded  amid  the  sand  and  mud  on  the  floor  of  an 
estuary  of  the  Carboniferous  period.  This  carbonaceous  matter 
probably  acted  as  a  precipitant  of  the  metal-bearing  solutions. 
As  the  depth  below  the  contact  increases,  the  rocks  lose  their 
blackness,  and  presumably,  therefore,  contain  no  precipitant 
carbon. 

Although  the  pay-ore  terminates  at  a  depth  fairly  uniform 
among  the  different  veins,  it  must  not  be  supposed  that  the 
veins  themselves  cease  at  this  horizon.  On  the  contrary,  the 
fractures  maintain  their  course  to  depths  far  beyond  the  deepest 
mine-workings;  but  they  become  barren  of  valuable  ore,  en- 
closing nothing  but  quartz  and  crushed  country.  The  rhodo- 
chrosite  ceases.  The  Lexington  tunnel,  for  example,  cuts 
through  the  lodes  which  have  yielded  so  richly  in  the  Enter- 
prise workings,  400  feet  overhead,  and  discloses  them  as  veins 
of  white  quartz,  traversing  light  gray,  coarse-grained  sandstone. 
Both  lode  and  country-rock  have  changed  in  character  entirely. 

The  fact  that  the  cross-veins  are  barren,  and  yet  rich  ore- 
bodies  overlie  them  in  the  contact-zone,  indicates  that  such 
bodies  are  due  to  special  shattering  of  the  ground  by  the  cross- 
veins,  which  has  furnished  favorable  places  for  ore-deposition. 
Moreover,  barren  as  the  cross-veins  are,  they  appear  to  influ- 
ence the  richness  of  the  pay-veins.  It  is  common  to  find  ores 
of  more  than  average  grade  in  the  pay-veins,  where  they  are 


THE    ENTERPRISE    MINE,   RICO,    COLORADO.  73 

broken  by  the  cross-veins.  But  the  mineral  solutions  appa- 
rently did  not  rise  through  the  cross-veins.  They  must  have 
circulated  along  the  verticals ;  and  the  deposition  of  ore  in  con- 
nection with  the  cross-veins,  as  noted,  may  have  been  not  only 
a  collateral,  but  even  a  secondary  process.  The  superior  rich- 
ness of  these  bodies  in  many  cases  may  indicate  that  they  have 
resulted  from  a  re-solution  and  re-deposition  of  the  contents  of 
the  verticals. 

The  idea  of  the  precipitation  of  the  ore  through  the  agency 
of  carbonaceous  matter  has  been  advanced  in  connection  with 
ore-deposits  in  other  regions.  I  may  quote  as  instances  the 
black  Silurian  slates  of  Bendigo,  Victoria;*  the  Devonian 
slates  of  Grympie,  Queensland;  the  Jurassic  slates  of  the 
"  mother  lode  "  region  in  Calaveras  and  Amador  counties,  Cali- 
fornia; the  black  shale  enclosing  the  gold-specimen  ores  of 
Farncomb  Hill,  Breckenridge,  Summit  county,  Colorado ;  the 
graphitic  casing  occasionally  seen  in  the  ores  of  the  Sunnyside 
and  Mastadon  veins,  inv  San  Juan  county,  Colorado;  and 
the  celebrated  Indicatorf  series  of  Ballarat,  Victoria. 

In  order  to  test  this  theory,  I  broke  some  pieces  of  black 
shale  on  the  contact  above  Raise  12  on  the  Enterprise  vein,  and 
took  tHem  to  the  Argo  smelter,  where,  by  the  kindness  of  Mr. 
Pearce,  the  following  experiments  were  made.  A  piece  of  the 
Rico  shale  was  put  into  a  weak  solution  of  sulphate  of  silver 
(AgSO4)  containing  some  free  acid  intended  to  neutralize  the 
lime  (CaCO3)  in  the  shale.  The  precipitation  of  metallic 
silver  became  visible  in  three  days.  The  parallel  experi- 
ment with  gold  was  more  interesting.  A  piece  of  ore  (as- 
saying 1147  ounces  of  gold  per  ton)  obtained  from  the  Prince 
Albert  mine  at  Cripple  Creek  was  taken,  and  its  gold  was  ex- 
tracted by  a  solution  containing  ferric  sulphate  (Fe2O33SO3), 
common  salt  (XaCl)  and  a  little  free  acid  (H4SO4).  This  Crip- 
ple Creek  ore  carried  the  black  oxide  of  manganese  (MnO2) 
in  visible  quantity,  and  thus  the  chlorine  used  to  form  the  gold- 
solution  was  liberated  in  a  manner  simulating  natural  condi- 
tions. Of  the  gold  in  this  Cripple  creek  ore,  99.91  per  cent. 

*  Discussed  by  the  writer  in  Trans.,  xxii.,  319  et  seq.  Also  by  Mr.  Argall, 
same  volume,  p.  762. 

f  See  also  "The  Indicator  Veins,  Ballarat,"  by  the  writer,  Eng.  &  Min.  Jour., 
Dec.  14,  1895. 


74         THE  ENTERPRISE  MINE,  RICO,  COLORADO. 

was  extracted,  and  subsequently  precipitated  on  the  Rico 
shale  by  inserting  the  latter  in  the  solution  thus  formed.  The 
gilding  of  the  black  shale  by  the  deposit  of  gold  became  visible 
within  four  hours. 

The  order  of  succession  of  the  various  minerals  composing 
the  ore  is  indicated  in  many  ways.  Beautiful  pseudomorphs 
of  quartz  after  baryta  have  been  found.  The  replacement  of 
rhodochrosite  by  quartz  is  often  discernible.  That  the  baser 
sulphides  frequently  enclose  fragments  of  rhodochrosite  (Fig. 
25),  establishes  their  relative  age.  Pieces  of  country  found 
within  the  vein-matter  are  occasionally  surrounded  by  a  rim  of 
rhodochrosite.  (See  Fig.  34.)  The  silver  sulphides,  and  the 
native  gold  associated  with  them,  occur  exclusively  within  the 
geodes  which  are  usually  distributed  along  the  center  of  the 
vein.  The  veins  enclose  shreds  of  country-rock;  sometimes 
such  pieces  of  rock  are  found  within  masses  of  sulphide  ore, 
and  there  is  an  imperceptible  graduation  from  clean  sulphide  to 
rock  so  impregnated  with  ore  as  to  have  its  true  character  ob- 
scured. Banded  structure  is  common. 

This  succession  points  to  the  following  conclusions :  When 
the  fractures  were  first  formed  they  consisted  of  lines  of 
crushed  c6untry,  afterwards  healed  by  a  deposit  of  carbonate 
of  manganese.  The  latter  (rhodochrosite)  is  likely  to  have 
been  derived  from  limestones  occurring  at  a  horizon  not  neces- 
sarily very  far  below  the  place  of  the  present  ore-deposits. 
Then  came  a  fresh  fracturing,  accompanied  by  the  deposition 
of  baryta  and  the  sulphides  of  lead  and  zinc.  Later  still  the 
earlier  vein-stuff  became  shattered  by  fissuring  on  the  old 
lines  of  movement,  and  along  the  water-way  thus  created  there 
came  siliceous  solutions,  which  replaced  baryta  and  rhodochro- 
sites  with  crystalline  quartz.  Finally,  the  vein  was  riven 
along  its  center,  and  waters  rich  in  the  salts  of  gold  and  silver 
found  their  way  upward  to  undergo  precipitation  through  the 
agency  of  the  rhodochrosite  and  the  shattered  portions  of  the 
carbonaceous  country  enclosed  within  the  vein-walls. 

We  are  driven  in  this  case  to  the  hypothesis  of  ascending 
solutions.  A  lateral  flow  must  be  a  part  of  an  upward  or  down- 
ward movement  of  the  underground  circulation.  As  a  general 
phenomenon  it  is  inconceivable.  The  deposition  of  ore  from 
descending  solutions  is  in  this  case  chemically  possible  through 


THE  ENTERPRISE  MINE,  RICO,  COLORADO.          75 

the  reduction  of  sulphates  by  carbonaceous  matter.  But  for 
the  hypothesis  of  descending  sulphates  there  is  no  basis  of  fact. 
The  geological  evidence  is  all  against  it.  The  structure  and 
environment  of  the  ore-bodies  point  to  their  derivation  from 
solutions  which  came  up  from  below.  The  passage-ways  open 
to  the  circulating  waters  cease  upward  and  extend  downward ; 
they  connect  with  no  available  origin  in  one  direction,  but  lead 
to  a  possible  source  in  the  other. 


\v 

Subject  to  Revision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


TEE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

BY   T.    A.    RICKARD,    MELBOURNE,   AUSTRALIA. 

(Cleveland  Meeting,  June,  1891.) 

AMONG  the  gold-deposits  discovered  in  recent  years  none  is  more 
extraordinary  in  richness  or  interesting  in  structure  than  that  of  the 
famous  mine  at  Mount  Morgan.  At  a  time  when  but  few  Aus- 
tralian mines  were  known  to  the  world  outside  the  colonies,  Mount 
Morgan  was  quoted  as  an  occurrence,  unusual  not  only  in  its  origin 
(for  it  was  said  to  be  due  to  geyser-action)  but  also  in  the  purity  of 
its  gold. 

The  mine  is  situated  just  within  the  tropics,  twenty-six  miles 
southwest  of  Rockhampton,  in  central  Queensland.  Queensland 
attained  in  1889  the  first  place  among  the  gold-producing  colonies 
of  Australasia,  a  position  previously  always  held  by  Victoria.  In 
that  year  Queensland  produced  737,822  ounces,  while  Victoria  came 
second  with  614,838  ounces.  Of  the  four  chief  mining  districts 
Rockhampton  stood  first,  as  the  following  figures  show: 

Quartz  crushed,         Yield,       Average  per  ton, 


Tons. 

Ounces. 

Oz.    Dwt. 

Rockhampton, 

.       81,138 

340,669 

4       2 

Charters  Towers,  . 

.     109,328 

165,551 

1     10 

Gympie, 

.     106,625 

112,847 

1       1 

Croydon, 

.      29,423 

51,156 

1     15 

It  should  be  added  that  Queensland  has  but  little  alluvial  mining, 
the  total  output  from  this  source  in  1889  being  only  5044  ounces, 
none  of  which  came  from  the  four  principal  gold-fields.  Leaving 
out  Rockhampton,  the  output  of  which  is  practically  that  of  the 
Mount  Morgan  mine,  it  will  be  noted  that  the  more  northerly  gold- 
fields  show  the  highest  average  (Gympie  being  furthest  from  and 
Croydon  nearest  to  the  equator).  This  is  largely  explained,  how- 
ever, by  the  increased  cost  of  milling,  due  chiefly  to  the  want  of 
water  for  batteries  and  the  consequent  economical  necessity  of  select- 
ing high-grade  material  only  for  crushing. 

During  the  year  ending  November  30,  1889,  the  Mount  Morgan 


2          THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

mine  produced  75,415  tons,  yielding  323,542  ounces,  13  dwts.,  13 
grs.,  worth  £1,331,484  18s.  5d.  (about  $6,657,424),  while  the  ex- 
penditure was  £227,769  19s.  Sd.  (say  $1,138,849)  permitting  the 
payment  of  £1,100,000  ($5,500,000)  in  dividends.  The  yield  per 
ton  was  4  oz.,  6  dwts.,  4  grs.,  while  the  working-cost  was,  as  is  seen, 
only  17  per  cent,  of  the  value  of  the  product.  These  figures  speak 
for  themselves. 

So  rich  a  mine  would  be  expected  to  have  some  romance  woven  about 
the  story  of  its  discovery.  Numerous  and  various  tales  are  told  of 
the  first  recognition  of  its  value,  but  the  best  authenticated  facts  are 
as  follows :  The  property  consists  of  the  original  selection  (No.  247) 
of  640  acres  taken  up  for  grazing  purposes,  in  1873,  by  Donald 
Gordon.  Becoming  acquainted  with  the  brothers  Morgan,  who  also 
held  land  in  the  district,  he  showed  them  one  day  a  piece  of  gold- 
bearing  quartz  which  he  had  picked  up  in  Mundic  creek.  For  a 
consideration,  stated  to  have  been  £20  and  as  much  whiskey  as  he 
could  drink,  Gordon  agreed  to  indicate  to  them  the  locality  of  the 
find.  On  the  hill  overlooking  the  creek  he  showed  them  the  siliceous 
ironstone,  some  of  which  can  still  be  seen  cropping  out  on  the  north- 
eastern slope.  The  stone  carried  visible  gold  ;  they  found  by  send- 
ing samples  to  Sydney  that  it  was  even  richer  than  they  had  imagined ; 
so  they  purchased  Gordon's  holding  at  £1  per  acre. 

The  three  Morgans  subsequently  sold,  first  a  part,  and  eventually 
the  whole,  of  their  interest  in  the  mine.  In  1886  a  company  was 
formed  with  a  capital  of  one  million  shares  of  £1  each.  These  shares 
rose  toward  the  end  of  1888  to  £17  5s.  (about  $86.25)  giving  the 
mine  a  market  value  of  seventeen  and  a  quarter  millions  sterling  or 
over  eighty-six  million  dollars.  The  shares  are  now  quoted  at  £7; 
for  Mount  Morgan,  to  quote  the  language  used  by  the  managing 
director  at  an  annual  meeting,  "  is  after  all  only  a  gold-mine  and  is 
consequently  subject  to  the  vicissitudes  of  all  mineral  formations," 
which  is  a  truism  too  often  forgotten  by  those  who  conduct  mining 
operations.* 

DESCRIPTION  OF  THE  MINE. 

The  mine  does  not,  as  its  name  would  imply,  crown  the  summit 
of  a  mountain,  properly  so  called,  but  forms  a  quarry  at  the  top  of  a 

*  Of  the  neighboring  companies  (and  as  might  be  expected  they  are  numerous, 
with  their  suggestions  of  an  extension  of  the  ore-deposit  in  such  names  as  Mount 
Morgan  West,  Mount  Morgan  Extended,  Mount  Morgan  North  Consols  and  so  on  ad 
nauseam)  none  have  proved  profitable,  notwithstanding  the  expenditure  of  much 
money  in  numerous  and  scattered  trial-shafts,  tunnels,  etc. 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.          3 

hill,  only  500  feet  above  the  village  at  its  base  and  1225  feet  above 
sea-level,  surrounded  by  very  broken  hilly  country  and  almost 
encircled  by  a  small  stream  (the  Mundic  creek  already  mentioned), 
and  in  many  respects  distinct  in  position  and  geological  structure 
from  the  hillocks  about  it.  From  the  summit  can  be  seen  the  level 
line  of  the  "  desert  sandstone/'  crowning  the  highest  ridges  of  the 
neighboring  hills — spurs  from  the  main  range  which  under  different 
names  (Blue  Mountains  in  New  South  Wales  and  Australian  Alps 
in  Victoria)  traverses  the  three  colonies  near  the  east  and  south- 
eastern coast  of  the  Australian  continent.  The  base  of  the  sandstone 
is  slightly  lower  than  the  summit  of  Mount  Morgan  and  overlies 
greywacke  and  quartzite.  Dykes,  of  at  least  two  periods,  form  an 
important  feature  of  the  structural  geology. 

The  crest  of  the  mount  is  being  rapidly  broken  away  in  the  quarry- 
ing operations  which  have  supplied  the  great  output  of  the  mine. 
The  removal  of  from  1200  to  1700  tons  a  week  makes  a  big  hole  in 
a  year.  While  the  greater  part  of  the  summit  has  been  thus  re- 
moved, the  northeast  slopes  still  show  the  croppings  which  first  ex- 
cited Gordon's  attention. 

The  ground  is  worked  in  terraces  or  benches,  30  feet  high  and  300 
feet  long.  At  the  date  of  my  visit  five  of  these,  started  at  various 
times,  could  be  seen,  though  but  little  remained  of  the  floor,  25  feet 
from  the  top,  which  formed  the  open  cut  first  put  into  the  ore.  A 
central  shaft  passes  from  the  floor  of  the  second  terrace  and  connects 
with  the  deeper  tunnels,  a  series  of  which  have  intersected  the  deposit 
in  various  directions.  This  shaft,  at  206  feet,  connects  with  the 
Freehold  tunnel,  the  main  ore-way  of  the  mine,  which  is  789  feet 
long.  The  next  deeper  tunnel,  called  No.  1,  starting  at  right  angles 
to  the  Freehold,  from  the  southern  face  of  the  hill  and  penetrating 
it  for  1070  feet,  is  155  feet  below  the  floor  of  the  lowest  surface- 
working  and  320  feet  below  the  original  summit.  This  No.  1 
tunnel,  though  only  33  feet  deeper  than  the  Freehold,  affords  a  very 
interesting  section  of  the  mountain  and  indicates  a  great  change  in 
the  form  of  the  ore-deposit.  It  is  the  deepest  of  the  adits  (for  adits 
and  not  strictly  tunnels  most  of  them  are),  except  the  "Sunbeam," 
which  had  been  started  at  the  time  of  my  visit;  but  it  had  not  been 
advanced  sufficiently  to  throw  any  additional  light  upon  the  struc- 
ture of  the  mountain. 

The  Mount  Morgan  ore  is  remarkable  for  its  extremely  hetero- 
geneous character.  The  frequent  alleged  discoveries  of  "  a  second 
Mount  Morgan,"  supported  by  similarity  of  the  specimens  exhibited 


4  THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

to  specimens  of  the  Mount  Morgan  ore,  are  not  to  be  wondered  at, 
in  view  of  the  great  difference  in  appearance  of  fragments  broken  in 
different  parts  of  the  same  heading  of  this  mine.  The  material 
quarried  in  the  upper  workings,  samples  of  which  are  now  to  be 
found  in  collections  and  museums  all  over  the  globe,  is  generally  so 
friable  and  shattered,  as  to  render  its  removal  with  the  aid  of  black 
powder  only,  very  easy.  Standing  in  one  of  the  open  cuts,  one  can 
see  faces  of  bluish-gray  crushed  quartz  very  similar  to  Comstock 
ore ;  masses  of  siliceous  hematite  (usually  considered  the  most  typical 
Mount  Morgan  stone)  resembling  the  croppings  of  ordinary  gold- 
veins,  whether  in  Victoria  or  California;  heavy  black  iridescent 
iron-stone  which  might  be  the  cap  of  a  silver-lode;  and  light- 
colored  reddish  ore  which  might  come  from  the  gossan  of  a  copper- 
mine.  Some  of  the  material  is  crushed  to  the  consistency  of  sugar, 
while  in  other  portions  of  the  mine  men  are  seen  employed  in  break- 
ing boulder-like  masses  of  ore.  Stalactitic  forms  occur  in  cavities, 
whilst  a  vermicular  and  reniform  appearance  is  also  not  uncommon. 
Very  rich  returns  were  obtained  from  a  body  of  bluish-black,  beau- 
tifully iridescent  ore.  The  Freehold  tunnel-workings  encountered 
a  patch  of  very  pure  white,  porous,  friable  "  sinter,"  so  light,  owing 
to  the  imprisoned  air,  that  it  would  float  on  water. 

Mount  Morgan  is  not  a  "specimen-mine/'  though  in  its  early 
history  it  furnished  very  lovely  pieces  of  gold-quartz,  some  of  which 
I  saw  in  Sydney.  They  consisted  of  an  iron  gossan,  containing  big 
"splashes"  of  gold,  of  the  size  of  a  thumb-nail.  As  a  rule,  how- 
ever, the  gold,  even  when  visible,  is  very  fine  and  scattered  thickly 
through  the  stone ;  but  owing  to  its  peculiar  character  (the  coating 
of  oxide  of  iron  to  be  referred  to  later  on)  it  is  not  readily  detected 
by  the  eye. 

Examination  of  the  many  varieties  of  ore  shows  that  while  there 
may  be  a  great  difference  in  outward  appearance,  due  to  coatings  of 
many-colored  oxides,  the  ore  is  always  substantially  quartzose.  As 
seen  in  the  surface-workings,  the  deposit  may  be  considered  a  mass 
of  quartzose  material  of  varying  color  and  specific  gravity,  traversed 
by  a  series  of  dykes  having  a  general  N.  W.  and  S.  E.  direction. 
Its  extent  is  approximately  indicated  by  the  various  workings  which 
intersect  the  hill.  In  the  upper  part  of  the  mine,  while  the  north 
and  northeastern  slopes  prove  it  to  be  continuous  in  these  directions, 
its  eastern  limit  has  been  reached  in  the  lower  floors  or  benches ;  and 
to  the  southwest  it  is  bounded  by  a  large  felstone  dyke,  which  forms 
the  most  marked  feature  of  the  surface-excavations.  The  first 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.  5 

tunnel  to  pierce  the  hill  is  No.  2,  which  starts  from  the  fifth  or 
lowest  floor,  running  N.  10°  E.  and  penetrating  120  feet  of  ore  before 
it  reaches  a  dyke.  This  is  probably  the  dyke  above  mentioned 
as  the  boundary  of  the  deposit  in  the  upper  floors;  but  here  it  has 
evidently  cut  into  the  deposit.  Beyond  this  dyke  the  tunnel  is  in 
ore  for  200  feet  further,  before  meeting  another  intrusion  of  felsitic 
matter,  which  extends  for  the  remaining  130  feet  to  daylight.  A 
branch-tunnel  proves  the  continuity  of  the  ore-body  eastward.  At 
this  level  the  stone  evidently  holds  out  most  satisfactorily,  and  is,  I 
believe,  for  the  most  part  auriferous.  It  is  a  porous  siliceous  mate- 
rial, varying  between  a  light  "sinter"  (sometimes  white,  sometimes 
iron-stained)  and  a  heavy  iron-stone,  often  manganic,  the  latter  in 
boulder-like  masses. 

The  next  tunnel  is  the  Freehold,  forming,  as  has  been  said,  the 
main  artery  of  the  mine.  It  connects  with  the  shaft  (sunk  from  the 
No.  2  floor),  and  from  the  mouth  of  it  a  tramway  carries  the  ore  to 
the  chlorination-works.  The  tunnel  starts  from  the  southeast  face 
of  the  hill,  traversing  a  decomposed  rhyolite  for  the  first  180  feet, 
and  then  cuts  through  40  feet  of  pyritiferous  quartzite,  a  rock  which 
here  first  makes  its  appearance  and  which  will  be  seen  to  play  an 
important  part  in  the  geology  of  the  locality.  Leaving  the  quartzite, 
the  tunnel  cuts  through  180  feet  of  a  rock  which  I  recognize*  as  a 
normal  dolerite.  The  innermost  portion  is  decomposed,  and  abuts 
against  a  much  altered  felspathic  rock.  This  brings  us  to  390  feet 
from  daylight ;  the  remainder  of  the  tunnel  (397  feet)  traverses  the 
ore-deposit.  The  ore  is  a  light  sinter-like  quartz,  often  iron-stained  ; 
but  while  it  contains  short  rich  patches  the  general  tenor  is  low. 
Near  the  junction  with  the  main  shaft,  almost  at  the  end  of  the 
tunnel,  a  branch  cross-cut  runs  southward  for  237  feet.  The  first 
J86  feet  are  in  the  deposit,  which  here  also  is  poor,  though  in  ap- 
pearance it  does  not  differ  from  the  richer  portions. f  The  next  20 
feet  traverse  the  dyke  which  at  this  point,  as  in  the  upper  floors, 
forms  the  limit  of  the  ore-body.  Beyond  this  there  is  only  to  be 
seen  the  pyritiferous  quartzite,  which  also  appears  in  a  short  cross- 
cut to  the  east. 

The  next  deeper  tunnel  is  Xo.  1,  only  33  feet  below  the  Freehold. 
I  was  denied  access  to  this,  and  am,  therefore,  indebted  to  a  govern- 


*  Thanks  to  microscopic  sections  shown  to  me  at  Charters  Towers  by  Mr.  Clarke. 
f  It  is  here  that  one  sees  the  light,  white,  pumice-like  material  which,  owing  to 
the  air  in  its  cavities,  will  float  on  water. 


6  THE    MOUNT   MORGAN    MINE,    QUEENSLAND. 

ment  report*  for  the  following  particulars  :  This  adit,  1070  feet  lon<r, 
starts  in,  and  traverses,  the  quartzite  of  the  country  for  132  feet  before 
passing  through  a  narrow  dyke;  it  then  passes  through  67  feet  more 
of  highly  pyritiferous  quartzite,  which  continues  to  within  12  feet 
of  a  shaft  coming  down  from  floor  No.  5.  There  next  succeeds  a 
large  felstone  dyke  (the  one  noted  as  cut  in  the  tunnel  above),  and 
the  remainder  of  the  adit  continues  in  pyritiferous  quartzite,  alter- 
nating with  numerous  dykes,  until  the  last  200  feet  are  reached, 
which  are  occupied  by  an  altered  dolerite.  The  auriferous  material 
of  the  upper  workings  was  represented  in  this  adit  by  25  feet  only 
of  siliceous  iron-stone.  Two  branch  cross-cuts  similarly  prove  the 
absence  of  the  deposit  in  this  part  of  the  mine  at  this  depth,  as  they 
also  intercept  the  quartzite  of  the  country. 

A  still  lower  tunnel,  the  Sunbeam,  starts  from  the  west  face  of  the 
mountain,  passing  through  pyritiferous  quartzite;  but  it  was  not 
advanced  sufficiently  at  the  time  of  my  visit  to  afford  any  evidence 
as  to  the  extent  of  the  ore-deposit. 

It  will  be  noted  that  the  largest  section  as  yet  obtained  of  the 
auriferous  portion  of  the  deposit  is  in  tunnel  No.  2,  where  its  dimen- 
sions are  356  feet  (26  feet  of  which  is  occupied  by  the  big  dyke)  ii> 
a  north  direction,  by  310  feet  east,  as  proved  by  a  branch  cross-cut. 
The  deposit  has  been  proved  to  extend  further  eastward  in  the  deeper 
levels  (Freehold  tunnel)  than  it  did  in  the  surface-excavations,  while 
on  the  other  hand  its  western  limits  are  more  restricted. 

THEORIES  OF  THE  FORMATION  OF  THE  ORE-DEPOSIT. 

The  origin  of  the  ore-deposit  has  been,  as  might  be  expected,  the 
theme  of  much  controversy.  The  earliest  description  came  from  Mr. 
R.  L.  Jack,  the  head  of  the  Queensland  geological  survey,  well 
known  as  a  careful  observer.  His  report  was  made  officially  for  his 
government  and  appeared  in  1881.  Others  have  contributed  their 
opinions  since;  and  meanwhile  the  rapid  development  of  the  mine,, 
more  particularly  by  the  deeper  adits,  has  furnished  additional  data 
for  a  problem,  of  which  the  following  solutions  have  been  offered : 

1.  That  the  deposit  is  that  of  a  geyser  (R.  L.  Jack). 

2.  That  it  is  an  auriferous  zone  traversed  by  a  series  of  quartz 
veins  of  auriferous  rnundtc  (J.  Macdonald  Cameron). 

3.  That  it  is  the  decomposed  cap  of  a  large  pyrite-lode  (the  view 
held  by  several  local  and  other  mining  engineers). 

*  R.  L.  Jack's  second  report,  which  will  be  referred  to  again. 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.  7 

The  Geyser- Theory. — The  first  of  these  explanations,  known  as  the 
"geyser-theory,"  was  promulgated  by  Mr.  Jack  in  his  first  report, 
dated  November  8,  1884.  It  has  found  its  way  into  many  scientific 
publications,  and  has  been  until  recently  the  most  widely  accepted. 
Citing  as  a  similar  occurrence  the  hot  springs  and  geysers  of  the 
Yellowstone  Park,  described  by  Dr.  A.  C.  Peale  in  the  United  States 
Geological  Survey  reports,  Mr.  Jack  observes  in  his  first  report: 
u  Nothing  but  a  thermal  spring  in  the  open  air  could  have  deposited 
the  material  under  consideration."  The  two  sections  shown  in  Figs. 
1  and  2  are  taken  from  that  report.  Of  Fig.  1,  he  says:  "The 
above  diagram  represents  my  idea  of  what  would  take  place  in  the 
case  of  a  geyser  remaining  in  activity  for  a  (geologically  speaking) 
lengthened  period."  The  original  form  of  the  ground  is  shown  by 
aa,  the  deposit  of  precipitated  material  by  66,  the  layer  of  solid 
material  at  cc,  while  the  surface-contour  is  indicated  by  dd.  In  de- 
scribing this  section  he  concludes,  "Such,  I  believe,  is  the  history  of 
Mount  Morgan  as  we  now  see  it." 

The  structure  of  the  mountain  is  supposed  to  be  shown  by  Fig.  2, 
in  which  Mr.  Jack  indicates  rhyolite  dykes  at  d  and  metamorphic 
rocks  at  s.  He  says  :  "a  is  the  pipe  of  the  geyser  (theoretical),  6 
the  cup-deposit  and  c  the  overflow  of  the  geyser." 

These  two  sections  have  found  their  way  into  scientific  publica- 
tions all  over  the  world,  and  have  been  for  a  long  time  accepted  as 
most  interesting  explanations  of  one  of  the  richest  of  modern  gold- 
mines. But  they  evidently  are  altogether  imaginary  and  theoretical. 

The  same  geologist  says,  in  his  description:  "After  the  cessation 
of  thermal  activity  the  powers  of  sub-aerial  denudation  would  come 
into  play.  Denudation  would  obliterate  the  lateral  terraces  which 
were  probably  not  absent  from  the  slopes  of  Mount  Morgan."  The 
information  obtainable  in  1884  as  to  the  nature  of  the  deposit  was 
totally  insufficient  to  enable  an  observer,  however  careful  and  ex- 
perienced, to  build  a  theory  upon.  The  amount  of  work  done  at 
that  time  was  mostly  limited  to  one  open  cut,  10  by  15  feet  in  size, 
which  showed  a  fan-like  arrangement  of  the  ore,  suggesting  to  Mr. 
Jack  the  structure  of  a  geyser.  It  was  an  altogether  local  appear- 
ance, as  was  proved  by  the  work  of  a  few  days  later. 

In  a  second  report,  dated  December  12,  1888,  Mr.  Jack  adds: 
"  The  evidence  now  to  hand,  in  my  opinion,  goes  far  to  confirm  my 
original  view  that  the  auriferous  material  was  deposited  by  a  thermal 
spring."  The  deposit  had  been  asserted  in  the  first  report  to  have 
been  formed  "  in  the  open  air,"  a  condition  constituting  the  whole 


THE    MOUNT   MORGAN   MINE,    QUEENSLAND. 


\  WA 


'  ,  -b 


\  /         /     N  N 

N-   v/;A\N  ^ 

.2>     Mvx  //  / ;  is  N 


THE    MOUNT    MORGAN    MINE,    QUEENSLAND.  9 

distinctive  value  of  the  theory,  which  otherwise  might  not  differ 
materially  from  the  views  accepted  as  to  the  aqueous  origin  of  ore- 
deposits  in  general.  In  the  second  report  the  author  declares  his 
theory  to  have  been  confirmed,  but  produces  evidence  which  really 
contradicts  its  essential  feature. 

Taking  the  two  reports  together,  we  find  that,  in  support  of  his 
explanation,  Mr.  Jack  adduces:  (a)  the  "fan-like  arrangement"  of 
the  material ;  (6)  "  the  frothy  and  cavernous  condition "  of  the 
siliceous  sinter;  (c)  the  hydrated  condition  of  the  silica  and  (d)  the 
fact  that  one  of  the  dykes  intersecting  the  country  does  not  also  in- 
tersect the  deposit. 

(a)  The  u  magazine"  face,  at  the  time  of  Mr.  Jack's  first  visit, 
appeared  to  him  to  have  a  distinctly  fan-like  structure.  But  little 
work  having  been  done  since  that  time  at  this  particular  point,  it 
should  be  possible  to  verify  this  statement;  but  the  most  careful 
observation  does  not  confirm  it.  The  cutting  shows  an  arrangement 
of  loose  material  such  as  can  frequently  be  seen  in  surface-excava- 
tions, probably  less  marked  now  than  when  first  seen  by  Mr.  Jack ; 
but  the  entire  absence  of  any  repetition  of  such  an  arrangement  of 
material  in  the  other  workings  must  destroy  its  value  as  evidence,  if 
it  ever  had  any. 

(6)  The  "  frothy  and  cavernous  "  condition  of  the  quartz  is  not 
peculiar  to  Mount  Morgan.  Those  who  are  familiar  with  the 
pocket-mines  of  California  will  remember  the  very  light,  pumice- 
like  quartz  which  often  accompanies  the  gold  in  those  mines.  It  is 
the  light  honeycombed  quartz  found  in  the  gossan  of  gold-veins  in 
many  places.  Generally  speaking,  the  Mount  Morgan  gangue  can 
be  duplicated  elsewhere ;  and  the  particularly  light  "  frothy  sinter," 
noticeable  as  a  patch  in  the  deeper  workings,  differs  only  from  the 
bulk  of  the  quartzose  ore  in  that  it  is  remarkably  free  from  accessory 
minerals.  It  is  the  siliceous  skeleton  produced  by  surface-decom- 
position of  more  than  ordinary  intensity.  It  is  possible  to  produce 
artificially  in  a  few  minutes,  by  the  application  of  acid  to  very  dis- 
similar iron-stone  ore,  a  material  similar  to  that  noted,  which  has 
undergone  the  chemical  action  of  underground  waters  during  long 
periods. 

(c)  The  hydrated  condition  of  the  silica  is  not  unusual  in  quartz- 
lodes,  and  while  it  is  valuable  as  evidence  to  disprove  the  suggestion 
that  the  ore  is  the  replacement  of  anhydrous  qtiartzite,  it  does  not 
necessarily  point  to  the  agency  of  a  geyser. 

(d)  The  intersection  of  the  country  by  a  dyke  which  does  not  pene- 


10  THE   MOUNT   MORGAN    MINE,    QUEENSLAND. 

trate  the  deposit  is  an  important  fact.  The  dyke  referred  to  is  that 
cut  by  tunnel  No.  1  at  120  feet  from  the  shaft  coming  down  from 
floor  No.  5.  Mr.  Jack  says,  at  the  end  of  the  second  report :  "  This 
shows  that  the  sinter  and  iron-stone  are  deposited  on,  and  were  not 
altered  portions  of,  the  pyritous  quartzite  country-rock."  Unfor- 
tunately the  evidence  is  far  from  conclusive.  In  describing  No.  1 
tunnel  the  dyke  is  referred  to  in  the  following  sentence:  "  A  quart- 
zose  rock  full  of  fine  pyrites  is  traversed  -for  the  next  37  feet,  when 
a  dolerite  or  rhyolite  dyke  is  cut.  The  direction  of  this  dyke  is  un- 
certain, as  the  tunnel  is  here  timbered  up."  In  his  descriptions  Mr. 
Jack  always  endeavors  to  draw  a  marked  distinction  between  the 
"  felstone "  dykes  which  penetrate  the  ore  and  the  "dolerite7'  and 
"rhyolite"  which  intersect  the  country-rock.  Now,  this  distinction 
is  arbitrary  and  misleading.  I  examined  the  rocks  both  in  situ  and, 
a  few  days  afterwards,  under  the  microscope.  The  dykes  penetrating 
the  deposit  are  so  decomposed  that  it  is  impossible  now  to  determine 
which  is  felstone  and  which  rhyolite.  The  dykes  cutting  through 
the  country  are  similarly,  but  not  to  so  great  a  degree,  decomposed, 
especially  in  the  vicinity  of  the  deposit.  The  statement  that  a 
"dolerite  or  rhyolite"  dyke  does  not  penetrate  a  deposit  which  is 
freely  intersected  by  decomposed  felspathic  eruptives,  should  be  sup- 
ported by  proof.  14;  is  not  so  here;  for  the  dyke  cut  in  No.  1  tunnel 
has  not  been  followed  upward,  and  in  the  south  branch  of  the  Free- 
hold tunnel,  just  overhead,  there  is  a  dyke,  which  is  possibly  the  one 
in  question. 

My  sections,  shown  in  Figs.  3  and  4,  will  illustrate  this.  The 
left  half  of  Fig.  4  resembles  one  of  Mr.  Jack's  sections,  being  taken 
along  a  nearly  identical  plane  (mine  is  taken  due  north  and  south). 
His  section,  however,  gives  a  curved  contour  to  the  limit  of  the 
deposit,  very  nicely,  but  unwarrantably,  suggesting  the  shape  of  a 
geyser-basin.  The  right  half  of  the  section  is  not  filled  in,  since 
this  part  of  the  mount  has  not  been  thoroughly  developed.  Fig.  3  is 
taken  along  a  line  E.  17°  S.,  and  is  obtained  by  projecting  the  cross- 
cuts from  the  No.  1  and  Freehold  tunnels  upon  the  plane  of  the  No. 
2  tunnel. 

In  further  considering  the  conditions  under  which  thermal  springs 
and  geysers*  exist,  and  the  similarity  of  such  conditions  to  those  ob- 
taining at  Mount  Morgan,  it  may  be  noted: 

1.  Isolated  geysers  are  unusual,  nothing  being  more  remarkable 

*  A  geyser  may  be  defined  as  a  thermal  spring  ejecting  material  in  the  open  air. 


THE  MOUNT  MORGAN  MINE*  QUEENSLAND. 


11 


than  the  exteuded  area  of  such  phenomena.  But  vigorous  and  ex- 
tensive prospecting,  such  prospecting  as  always  follows  great  min- 
eral discoveries,  has  not  led  in  this  region  to  the  finding  of  anything 


similar  to  Mount  Morgan  or  to  a  geyser.  It  is  true,  there  is  a  small 
hillock  adjoining  the  mount  to  the  northwest  (called  Callan's  Knob) 
where  somewhat  similar  material  has  been  found  ;  but  it  may  be 
considered  as  an  offshoot  or  spur  from  the  main  deposit. 


12         THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

2.  Geysers  have  terrace-formations  due  to  the  overflow  of  the 
siliceous  or  calcareous  waters.     The  map  accompanying  Mr.  Jack's 
first  report  indicated  "the  overflow  from  the  hot  spring"  as  cover- 
ing an  area  of  2000  by  3000  feet.     But  this  was  purely  a  guess,  for 
such  overflow-material  is  not  to  be  seen ;  had  the  terraces  existed, 
and  had  they  been  removed  by  denudation,  would  not  the  adjoining 
river  beds  show  some  accumulations  of  their  detritus? 

3.  Geysers  have  a  central  vent,  which,  when  the  geyser  becomes 
extinct,  is  found  to  be  choked   up  with  sinter.     Though   Mount 
Morgan  has  been  traversed  by  a  number  of  adits  and  cross-cuts,  not 
to  mention  extensive  surface-excavations,  no  such  vent  and  no  such 
central  column,  or  anything  suggestive  of  either,  has  been  seen. 

The  Network- Theory. — The  second  explanation  is  that  of  J.  Mac- 
donald  Cameron,  namely,  that  it  is  a  network  of  quartz  veins.  This 
opinion  was  expressed  in  a  report  to  the  directors  of  the  company, 
dated  March  26,  1887.  The  following  passage  outlines  the  author's 
ideas:  "It  (Mount  Morgan)  may  be  considered  as  consisting  of  a 
net-work  of  quartz  veins,  about  200  feet  in  width,  traversing  on  the 
one  hand  a  metamorphic  matrix  of  a  somewhat  argillo-arenaceous 
composition,  largely  impregnated  where  it  has  been  exposed  to  at- 
mospheric influence  with  oxides  of  iron,  and  on  the  other  hand  what 
appears  to  be  a  felspathic  tufaceous  igneous  rock/'  The  author  ad- 
vances no  proof  that  such  is  the  case.  What  evidence  he  does  give 
is  couched  in  the  vaguest  phraseology.  This  explanation  is  proved 
untenable  by  the  same  reasons  as  those  which  apply  to  the  third 
theory  now  to  be  considered. 

The  Lode-Theory. — The  view  that  this  deposit  is  the  decomposed 
cap  of  a  pyrites  lode,  has  derived  fictitious  importance  from  the  fact 
that  it  is  alleged  to  be  the  opinion  of  the  mine-manager  and  others 
interested  in  the  property.  Such  a  view  has  been  the  excuse  for  the 
large  number  of  "extended"  companies  (they  call  them  "pups"  in 
Victoria),  companies  which,  in  the  light  of  our  present  knowledge, 
were  almost  certainly  foredoomed  to  failure.  The  prevalence  of  the 
lode-theory  in  the  early  days  of  mining  at  Mount  Morgan  is  not  to 
be  wondered  at,  however  little  warrant  there  may  be  for  it  now.  It 
was  due  to  the  existence  of  mundic  veins  in  the  vicinity,  the  casts  of 
pyrites  crystals  found  in  the  ore,  and  the  neighborhood  of  the  pyri- 
tiferous  quartzite,  the  true  relation  of  which  was  not  known,  or  if 
known,  was  kept  very  quiet.  The  well-marked  limits  of  the  great 
deposit,  as  outlined  by  the  deeper  developments  of  the  last  two  years, 
completely  disproves  this  theory  and  that  of  Cameron.  No  doubt, 


THE   MOUNT   MORGAN    MINE,   QUEENSLAND.  13 

\ 

the  assertion  of  the  continuity  of  the  gold-bearing  rock,  even  though 
it  should  become  pyritiferous,  has  fascinations  for  a  shareholder 
which  even  a  geologist  can  understand.  But  the  deeper  tunnels 
have  proved  that  lode-structure  is  entirely  absent,  and  that  the  de- 
posit lies  upon,  but  is  not  an  altered  portion  of,  the  pyritiferous 
quartzite  of  the  country. 

The  Theory  of  Metamwphosis  and  Replacement. — The  more  than 
ordinary  size  and  value  of  the  Mount  Morgan  ore-deposit,  the  ro- 
mantic history  of  its  discovery  and  its  subsequent  marvellous  pro- 
duction, have  all  helped  to  place  it  outside  the  ordinary  type  of 
mineral  occurrence.  This  is  often  the  case  with  new  discoveries, 
and  it  is  not  the  first  time  that  the  geyser  has  been  a  deus  ex  machina 
to  a  perplexed  geologist.  The  splendid  work  done  in  recent  years 
by  Sandberger,  Daubree  and  others  in  the  study  of  the  chemical 
change,  and  the  distribution  by  underground  waters,  of  the  minerals 
of  the  older  rocks  has  led  to  a  gradual  substitution,  for  theories  of 
eruption,  or  direct  igneous  agencies  in  general,  of  the  belief  in  the 
capability  of  aqueous  agencies  to  bring  about  most  of  the  phenomena 
of  ore-deposition.  Moreover,  the  action  of  percolating  solutions  on 
the  minerals  of  the  crystalline  rocks,  and  subsequent  interchange 
with  the  more  soluble  portions  of  the  neighboring  rock-masses,  have, 
to  a  great  extent,  replaced  the  assumptions  of  the  old  ascension- 
theories.  The  view  that  the  more  ore-deposits  are  studied  the  more 
frequently  they  will  be  found  to  be  in  great  part  the  product  of  the 
replacement  of  the  country-rock  is  gaining  ground,  and  has  been 
much  strengthened  by  the  researches  of  Becker  at  Virginia  City, 
Curtis  at  Eureka,  and  Emmons  at  Leadville,  as  contained  in  the 
monographs  published  by  the  U.  S.  Geological  Survey,  monographs 
(the  last-mentioned,  particularly),  which  are  the  classics  of  modern 
economic  geology.  This  view,  which  underground  experience  is 
continually  confirming,  has  explained  many  of  the  more  unusual 
types  of  ore-deposition  in  Europe  and  America,  and  I  believe  it  will 
apply  to  Mount  Morgan. 

The  explanation  suggested  is  this  :  that  the  ore-deposit  of  Mount 
Morgan  represents  an  altered  portion  of  shattered  country-rock, 
which,  by  reason  of  its  crushed  condition,  was  readily  acted  upon  by 
mineral  solutions,  and  that  these  solutions  replaced  the  basic  and 
felspathic  with  acidic  and  quartzose  material,  which  was  also  gold- 
bearing.  It  is  its  quartzose  and  permeable  character  which  has  saved 
from  disintegration  the  mass  thus  affected,  and  has  preserved  it  as 
an  ore-body  on  the  summit  of  the  hill. 


14         THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

A  case,  in  many  respects  very  similar,  occurs  in  the  Red  Mountain 
basin,  Colorado,  and  the  following  description  given  by  Mr.  Em- 
mons*  is  clearly  in  point : 

"  Instead,  however,  of  being  surface-deposits,  they  (the  Red  Mountain  deposits) 
are  simply  portions  of  the  andesitic  country-rock  from  which  acid  waters  have  re- 
moved the  basic  constituents,  perhaps  depositing  a  certain  amount  of  silica  in  their 
place ;  the  resulting  quartzose  masses,  offering  greater  resistance  to  the  disintegrat- 
ing effect  of  atmospheric  agents  and  to  erosion  than  the  surrounding  rocks,  have 
been  left  as  mound-like  ridges  protruding  above  the  general  surface,  more  or  less 
independent  of  the  natural  drainage-channels." 

This  explanation,  curiously  enough,  was  also  given  to  disprove  a 
geyser-theory,  but  the  deposits  in  question  seem  to  possess  scientific 
interest  only. 

Deposits  of  somewhat  kindred  origin  are  the  Yankee  Girl  and 
Bassick  mines  in  Colorado.  The  former,  a  well-known  mine  in  the 
San  Juan  district,  is  perhaps  the  more  suggestive,  since  in  that  case 
several  fracture-planes  meet  to  form  a  wedge-shaped  mass  of  rock, 
which  has  been  so  acted  upon  by  percolating  waters  as  to  become  a 
"chimney  "  of  very  valuable  silver-ore. 

To  return  to  the  particular  conditions  which  obtained  in  the  dis- 
trict under  discussion:  The  country  around  Mount  Morgan  consists, 
in  descending  series,  of  sandstone,  greywacke,  quartzite,  shales  and 
occasional  bands  of  serpentine.  Intrusive  masses  of  dolerite  inter- 
penetrate the  country,  and  often  occupy  a  position  between  the 
originally  stratified  rocks.  The  sandstone  is  known  in  the  geology 
of  Queensland  as  "  Daintree's  desert  sandstone,"  and,  by  virtue  of  a 
recent  discovery  of  fossil  remains,  may  be  labelled  as  Cretaceous.  The 
greywacke  has  not  been  recognized  as  such  on  the  Mount  itself,  but 
it  underlies  the  sandstone  in  other  parts  of  the  district.  It  is  a  mix- 
ture of  silico-felspathic  material,  which  shades  off  into  a  grey wacke- 
slate,  and  is  usually  so  much  altered  as  to  be  scarcely  distinguishable 
from  a  true  eruptive.  The  quartzite  has  a  bluish-gray  color,  and  is 
highly  -pyritiferous,  the  pyrites  carrying  traces  of  gold. 

The  shales  are  usually  so  indurated  and  altered  as  to  resemble 
closely  the  crystalline  rocks.  The  dolerite",  when  fresh,  is  a  typical 
rock  of  its  class,  and  in  various  intrusive  forms  is  cut  through  by 
most  of  the  prospecting-shafts  at  the  base  and  around  the  mountain. 
The  serpentine  is  of  very  limited  occurrence.  Some  uncertain,  un- 
determined decomposed  rocks,  which  have  also  been  called  dolerite, 

*  "Structural  Relations  of  Ore-Deposits."  —  Transactions,  xvi.,  809. 


THE    MOUNT   MORGAN    MINE,    QUEENSLAND.  15 

are  probably  metamorphosed  greywacke.  The  country  is  freely  in- 
tersected by  dykes  of  varying  composition,  especially  near  the  ore- 
deposit. 

The  history  of  these  rocks  I  read  somewhat  as  follows :  A  period  of 
dynamic  disturbance  is  indicated  by  the  intrusions  of  dolerite,  which, 
by  extreme  metamorphism,  might  have  changed  a  dolomite  into  the 
serpentine  we  now  see  ;  would  have  indurated  the  shales  so  that  they 
are  scarcely  to  be  distinguished  from  the  crystalline  rocks;  and 
would  also,  accompanied  by  chemical  alteration,  change  a  ferrugi- 
nous red  sandstone  into  a  bluish-gray,  highly  pyritiferous  quartzite. 
Approaching  the  surface,  the  same  energy  would  be  expended  in 
the  fracturing  of  the  quartzite  and  greywacke;  the  intrusive  dolerite 
would  rise  through  the  fissures  in  the  shattered  rocks,  form  ing  dykes, 
which,  meeting  a  silico-felspathic  granular  rock  (the  greywacke), 
would  give  it  a  semi-crystalline  character.  The  sandstone  would 
similarly  be  vitrified.  Later  movements  would  result  in  the  further 
intersection  of  this  part  of  the  district  by  the  numerous  dykes,  the 
decomposed  remains  of  which  are  now  to  be  seen  ramifying  through 
the  deposit.  Those  gradual  chemical  interchanges  would  take  place 
which  resulted  in  the  alteration  of  the  shattered  country-rock,  and 
its  becoming  a  portion  of  the  gangue  inclosing  the  auriferous  ma- 
terial, which  was  then,  or  at  a  later  time,  deposited.  In  process  of 
time,  subaerial  denudation  removed  the  sandstone,  which  now  is  only 
to  be  seen  on  the  further  summits  of  the  neighboring  hills.  At- 
mospheric agency  continued  to  carve  away  the  less  siliceous  and  less 
porous  portions  of  the  country  surrounding  the  deposit,  until  Mount 
Morgan,  owing  to  the  pervious,  quartzoze  nature  of  its  crest,  re- 
mained as  a  low  hill  in  an  undulating  country. 

The  district  of  Mount  Morgan  has  undergone  extreme  metamor- 
phism,  accompanied,  as  such  metamorphism  frequently  is,  by  those 
chemical  reactions  which  more  or  less  completely  alter  the  rocks  acted 
upon. 

It  is  probable  that  there  was  more  than  one  period  of  such  ac- 
tivity, alternating  with  intervals  of  rest,  during  which  the  pressure 
of  overlying  rock-masses  and  the  cementing  action  of  the  under- 
ground waters  would  slowly  re-solidify  the  more  or  less  shattered 
rocks. 

The  deposit  occupies  a  shattered  portion  of  country-rock,  freely 
intersected  by  dykes.  The  largest  dyke  in  the  upper  workings  cuts 
through  the  ore  at  one  level,  while  it  bounds  it  at  another.  It  seems 
in  keeping  with  experience  elsewhere,  to  suppose  that  the  dykes 


16  THE   MOUNT   MORGAN    MINE,    QUEENSLAND. 

penetrating  the  country  formed  passages  along  the  line  of  contact, 
through  which  and  around  which,  by  the  agency  of  mineral  solu- 
tions, the  deposition  took  place,  sometimes  on  one  side  only,  some- 
times on  both,  the  physical  condition  of  the  different  portions  deter- 
mining, in  a  large  measure,  the  extent  of  such  deposition  and  re- 
placement. It  is  also  probable  that,  after  the  formation  of  the  de- 
posit, later  movements  caused  the  circulation  of  fresh  mineral-bear- 
ing solutions,  which  would  lead  to  the  enrichment  of  the  deposit  at 
certain  points,  and  so  explain  the  irregular  tenor  of  the  ore. 

The  evidence  at  hand  is  not  sufficient  to  enable  us  to  determine 
the  particular  rock  in  which  the  deposit  was  formed,  and  which  it 
almost  entirely  replaced  ;  but  it  could  not  have  been  the  underlying 
quartzite,  the  line  of  contact  with  which  shows  no  .gradation  into 
the  ore ;  and  of  the  other  two  possible  rocks,  the  grey  wacke  and  the 
sandstone,  the  indications  point  to  the  former.*  In  the  neighbor- 
ing prospecting-shafts,  auriferous  quartzose  material  resembling  that 
of  Mount  Morgan  has  been  found  to  pass  into  a  grev  wacke  or  grey- 
wacke-slate,  which,  in  turn,  overlies  the  pyritiferous  quartzite.  Silicate 
of  alumina  is  generally  present  throughout  the  deposit.  The  char- 
acter of  the  ore-material  is  such  as  would  result  from  the  alteration 
of  a  silico-felspathic  rock  by  the  action  of  mineral-bearing  solutions. 

The  numerous  dykes  which  penetrate  the  deposit  are  the  evidence 
and  the  result  of  the  dynamic  agency  which  fissured  the  country- 
rock,  and  in  so  doing  prepared  a  ready  passage  for  the  underground 
waters.  These  waters,  while  they  may  have  been  "  thermal "  (i.  e., 
of  a  temperature  above  the  mean  annual  temperature  of  the  district, 
as  are  most  underground  waters),  yet  did  not  undergo  precipitation 
"in  the  open  air."  The  brecciated  forms  which  the  ore  sometimes 
assumes  scarcely  require  the  explanation  offered  by  Mr.  Jack,  who 
states  that  "  the  occasionally  angular  condition  of  the  sinter  and 
tumbled  condition  of  the  ironstone  masses,  would  appear  to  indicate 
that  explosive  discharges  of  gases  or  steam  occurred  at  intervals 
with  sufficient  violence  to  disturb  the  deposits  accumulated  by  the 
thermal  spring."  Would  it  not  be  simpler  to  suppose  the  fracturing 
of  the  rock,  of  which  there  is  abundant  evidence,  to  have  produced 
irregular  pieces,  which  would  subsequently  become  partially  rounded 

*  The  position  of  the  grey  wacke  has  been  shown  to  be  between  the  quartzite  and 
the  sandstone.  The  original  summit  of  the  Mount  is  but  little  below  the  level  of 
the  base  of  the  sandstone,  while  the  deposit,  as  we  have  seen,  overlies  the  quartzite. 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.         17 

by  the  solvent  action  of  the  waters  percolating  through  their  inter- 
stices ?  * 

At  Mount  Morgan  all  the  conditions  generally  considered  favor- 
able to  ore-deposition  were  present  in  a  marked  degree.  A  mass  of 
country-rock,  whether  greywacke  or  sandstone,  consisting  of  granules 
of  quartz,  held  together  by  a  felspathic  cement,  f  becomes  fractured 
by  the  intrusion  of  a  series  of  dykes,  which  form  a  ready  passage  for 
the  flow  of  mineral  solutions.  Such  a  rock  would  readily  lend 
itself  to  alteration,  and  would  be  well  fitted  to  receive  a  mineral 
deposit.  Later  dynamic  action  produced  a  further  metamorphism  of 
the  surrounding  rocks,  followed  or  accompanied  by  the  intersection 
of  the  already  shattered  rocks  by  another  series  of  dykes,  which  re- 
opened a  passage  for  the  underground  waters.  In  this  case  it  is  not 
necessary  to  go  far  for  the  source  of  the  gold.  The  large  mass  of 
decomposed  pyritic  quartzite,  though  the  pyrites  contains  but  a  trace 
of  the  precious  metal,  is  more  than  sufficient  to  account  for  the 
wealth  that  has  been  uncovered. f 

This  theory  explains  several  points  which  have  been  the  source  of 
perplexity,  more  particularly  the  want  of  regularity  in  structure, 
which  was  as  much  opposed  to  the  geyser-  as  to  the  lode-theory. 
The  great  uneven  ness  of  the  gold-contents,  the  frothy  state  of  the 
onartz,  ^0  often  noted,  and  also  its  hydrous  condition,  may  be  due  to 


*  Since  writing  the  above,  I  have  visited  and  examined  the  equally  famous  Broken 
Hill  silver-deposit.  AVhen  I  declared  that  the  material  of  the  Mount  Morgan  ore  was 
not  unique,  that  it  could  be  duplicated  elsewhere,  and  that  it  did  not,  perse,  require 
any  extraordinary  explanation,  I  did  not  expect  to  see  so  soon  an  instance  confirm- 
ing my  statement.  The  huge  outcrop  of  the  Broken  Hill  silver-lead  lode  has  much 
to  remind  one  of  the  big  gossan  of  the  Queensland  gold-mine.  Indeed,  if  one 
stands  in  the  quarry  between  Brodribb's  and  Patterson's  shafts  one  might  easily 
imagine  oneself  on  floor  No.  3  of  Mount  Morgan.  The  face  has  the  same  singular, 
broken  appearance,  consisting  of  masses  of  ochreous  earth,  bands  of  hard,  siliceous 
ironstone,  bodies  of  black  manganic  ore,  together  with  portions  of  white  kaolin ized 
material  (here  undoubtedly  altered  inclusions  of  country-rock,  and  not,  as  at  Mount 
Morgan,  decomposed  felstone  dykes).  Both  at  the  surface  and  underground,  the 
sintery  stalactitic  structure  which  is  found  at  Mount  Morgan  also  occurs.  The  hy- 
drated  iron-ores  produce  the  same  "frothy,"  "cavernous"  material,  supposed  to  be 
so  suggestive  of  a  geyser — and  this,  too,  not  in  isolated  patches  only,  but  wide- 
spread. I  may  add,  that  there  is  no  doubt  whatever  that  the  Broken  Hill  is  a  "  true 
fissure  "-lode,  traversing  the  metamorphic  rocks  of  the  district  (schists,  garnet- 
iferous  sandstone,  and  quartzite,  principally  the  first),  independent  of  their  strati- 
fication. 

f  The  underlying  quartzite  may  not  be  the  only  source  of  the  gold,  for  it  is  note- 
worthy that  the  "desert  sandstone"  has  been  known  to  be  auriferous,  such  gold  being 
waterworn  and  sedimentarv. 


18         THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

later  precipitation  in  cavities  already  formed  by  the  solvent  action  of 
the  waters  on  the  shattered  portions  of  rock.  Finally,  there  is  no 
need  to  offer  any  particular  reason  for  the  unusual  richness  of  the 
deposit,  beyond  the  eminently  favorable  physical  condition  of  the 
original  rock,  the  numerous  channels  offered  to  percolating  waters 
and  the  close  proximity  both  of  the  source  of  the  gold  and  of  the 
usual  precipitants. 

Whether  this  be  a  correct  explanation  of  the  facts,  time  and  the 
further  development  of  the  mine  will  probably  decide.  It  may  cer- 
tainly be  said,  without  fear  of  contradiction,  that  few  mines  offer 
such  an  interesting  field  for  geological  speculation.* 

TREATMENT  OF  THE  ORE. 

The  Mount  Morgan  chlorination-works  are  among  the  most 
successful  and  extensive  now  in  operation.  The  complete  success  of 
the  treatment  is  largely  due  to  the  extremely  friable  character  of  the 
ore,  which  renders  it  pulverization  easy,  while  its  porosity  assists 
materially  in  the  thorough  chlorination  of  the  gold.  An  enthu- 
siastic writer  has  spoken  of  the  ore  as  "  a  sort  of  snow-drift,  which 
melts  in  the  chlorination-vats  of  the  company  into  a  golden  sand, 
such  as  might  be  supposed  to  have  been  brought  from  the  bed  of  the 
river  Pactolus,  instead  of  from  the  top  of  an  Australian  mountain." 

The  capacity  of  the  present  works  is  1800  tons  per  week.  The 
gradual  alteration  and  enlargement  of  the  method  of  treatment  is 
shown  by  the  stamp-mill  and  the  two  chlorination-plants.  The  mill 
(25  stamps)  by  the  side  of  Dee  creek,  is  a  reminder  of  early  at- 
tempts at  the  extraction  of  the  gold  by  ordinary  amalgamation.  The 
rock  which  the  battery  was  called  upon  to  crush  averaged  10  ounces 

*  Since  I  wrote  the  above  there  has  come  into  my  hands  the  report  of  the  Mount 
Morgan  Gold  Mining  Company,  Limited,  presented  at  the  last  annual  meeting, 
and  giving  information  up  to  July,  1890.  It  is  accompanied  with  maps  and  sec- 
tions, notably  calculated  to  yield  a  minimum  of  information.  It  appears  from  the 
report  that  later  developments  have  added  but  little  to  the  known  extent  of  the 
ore-body,  the  main  feature  of  the  later  exploration  being  the  driving  of  a  cross-cut 
south  from  the  Freehold,  at  800  feet  from  its  mouth,  proving  the  extension  of  the 
deposit  at  this  line  and  in  this  part  of  the  mine — as  was  to  be  expected,  seeing  that 
its  dip  is  toward  the  mouth  of  the  Freehold. 

Up  to  November  30,  1890,  the  mine  had  paid  the  present  company  £2,358,333  in 
dividends,  the  total  gold  obtained  being  756,042  ounces,  worth  £3,121,741.  During 
the  last  six  months  (ending  November  30,  1890)  37,867  tons  of  stone  were  treated 
and  yielded  113,251  ounces  of  golcl,  or  an  average  of  2  ounces  19  dwts.  per  ton. 
Nearly  all  this  came  from  the  upper  workings. 


THE    MOUNT    MORGAN    MINE,    QUEENSLAND.  19 

per  ton,  but  the  contents  of  the  tailings  proved  of  much  greater 
value  than  the  amount  of  amalgam  obtained..  This  led  to  a  critical 
examination  of  the  ore  at  the  Sydney  Mint.  It  was  found  that  the 
bullion  was  of  a  fineness  hitherto  unknown  in  nature,  assaying  99.7 
per  cent,  occasionally  99.8,  of  pure  gold,  the  rest  being  copper, 
with  a  trace  of  iron.  It  is  remarkable  as  being  almost  entirely  free 
from  silver.  Its  value  per  ounce  was  £4  4s.  8d,  pure  gold  being 
worth  at  the  London  Mint  £4  4s.  \\ld.  Dr.  Liebius,  of  the  Sid- 
ney Mint,  considered,  as  the  result  of  numerous  experiments,  that 
the  iron  present  was  in  the  form  of  an  oxide,  which  coated  the  gold 
and  so  prevented  its  contact  with  the  mercury.*  Parcels  of  the  ore 
were  then  sent  to  the  Technological  Museum  at  Melbourne,  where 
Messrs.-  Newberry  and  Vautin  subjected  it  to  numerous  tests.  It 
was  found  that  when  dehydrated  by  heat  it  became  less  refractory; 
and  its  treatment  by  chlorine  was  suggested.f  The  ordinary  Platt- 
ner  process,  as  worked  in  California,  was  found  quite  unsuitable, 
owing  to  the  extremely  fine  crushing  which  it  required,  and  which 
resulted  in  the  formation  of  slimes,  greatly  hindering  subsequent 
filtration.  It  was  then  that  Mecsrs.  Newberry  and  Vautin  planned 
the  method  which  has  since,  with  the  addition  of  some  mechanical 
details,  been  patented  under  their  joint  names.  J 

While  the  stamp-mill  proved  incapable  of  extracting  a  proper 
percentage  of  the  gold,  the  peculiar  character  of  the  ore  is  remark- 
ably suited  by  the  process  now  in  use.  The  extremely  minute  state 
of  subdivision  of  the  gold  and  the  very  friable  nature  of  the  gangue 
caused,  in  wet.  stamp-milling,  a  considerable  loss  in  "float,"  carried 
away  in  the  readily-formed  slimes;  but  the  character  of  the  ore  indi- 
cated that  dry  crushing  would  prove  effective ;  and  hence  the  early  in- 
troduction of  Krom  rolls  was  the  first  great  improvement  made.  The 
old  works,  which  are  just  above  the  stamp-mill,  receive  their  supply 

*  My  own  experience  witli  the  ores  of  Gilpin  county,  Colorado,  leads  me  to 
believe  that  this  is,  more  frequently  than  is  usually  supposed,  the  obstacle  to  suc- 
cessful amalgamation. 

f  It  had  been  previously  treated  with  chlorine  by  Limberner  at  Gympie. 

%  The  mine-manager  informed  me  that  nothing  of  the  original  Newberry -Vautin 
plant  remained  save  a  piece  of  old  shafting.  The  Mount  Morgan  Company  bought 
the  right  to  use  the  process,  and  hence  does  not  pay  anv  royalty.  While  the  origi- 
nal plant  has  been  entirely  replaced,  it  cannot  fairly  be  said  that  the  method  of 
treatment  has  been  changed,  or  that  it  is  any  other  in  its  main  features  than  that 
known  by  the  names  of  those  who  first  adopted  it.  Into  the  question  of  the  origi- 
nality of  the  process  it  is  not  within  the  province  of  this  paper  to  enter.  It  has 
been  ably  discussed  by  the  Xew  York  Engineering  and  Mining  Journal. 


20         THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 

on  an  aerial  tramway,  three-fourths  of  a  mile  long,  with  a  total  fall 
of  400  feet.  It  is  of  the  Hallidie  type,  uncommon  in  the  colonies, 
but  familiar  to  American  mining  engineers,  and  need  not  therefore  be 
here  described.  The  feeding  of  the  buckets  (of  which  there  are 
sixty)  is  admirably  effected  by  the  use  of  a  travelling  supply-bucket. 
The  old  works  contain  two  rock-breakers,  one  revolving  ore-dryer, 
four  sets  of  rolls,  ten  furnaces,  fourteen  barrels,  twenty-six  vats  and 
twenty-eight  filters.  The  power  is  supplied  by  one  40-H.  P. 
(nominal)  engine  and  two  30-H.  P.  boilers.  The  practice  in  these 
works  is  identical  with  that  in  the  new  works  about  to  be  described. 

The  new  works,  ejected  on  the  higher  slope  of  the  mountain, 
about  400  feet  from  the  summit,  while  somewhat  similar  to  the 
lower  works,  show  improvements  in  arrangement,  besides  allow- 
ing the  necessary  fall  for  the  tailings.  The  ore,  coming  from  the 
open  cuts  and  the  Freehold  tunnel  by  a  series  of  inclines  (some  of 
which  are  automatic  gravity-tramways)  passes  through  two  Blake- 
Marsden  rock-breakers,  and  is  then  dried  in  two  revolving  cylin- 
drical furnaces,  self-discharging  after  the  manner  of  a  trommel.  The 
rotation  is  produced  by  an  external  cog-wheel.  Thence  the  dried 
material  goes  to  Krom  steel  rolls,  arranged  in  two  series  of  three 
each.  Each  set  of  rolls  is  followed  by  a  revolving  sieve,  the  coarse 
stuff  passing  into  an  elevator  which  returns  it  for  second  crushing, 
while  the  fine  passes  on  to  the  second  rolls  and  thence  to  the  third. 
The  last  pair  of  rolls  pulverizes  the  ore  twice  before  it  is  carried  by 
a  worm-conveyor  to  an  elevator  which  sends  it  to  a  chamber  above 
the  furnaces.  An  80-H.  P.  compound  engine  drives  the  rolls  and  a 
20-H.  P.  engine  the  breakers  and  revolving  dryers,  while  two  Root 
blowers  are  employed  in  the  removal  of  the  dust,  of  which  there  is 
a  great  deal.  Five  Cornish  boilers  of  30-H.  P.  each  supply  the 
necessary  steam. 

The  furnace-chamber  is  400  by  120  feet  in  size,  and  contains  18 
ordinary  reverberatory  furnaces,  each  having  a  capacity  of  1  ton. 
The  heat  to  which  the  material  is  here  exposed  is  a  cherry-red,  such 
as  will  get  rid  of  organic  matter,  water  of  crystallization,  etc.,  but 
does  not  approach  that  of  a  thorough  calcination.  At  the  end  of  3 
hours  the  charge  is  removed  and  spread  upon  the  cooling-floors. 
When  it  has  cooled  it  is  trucked  to  the  21  iron  hoppers  which  sup- 
ply 21  chlorination-barrels.  The  charge  for  chlorination  is  1  ton 
of  pulverized  ore,  90  gallons  of  water,  40  to  50  pounds  of  sulphuric 
acid  and  35  pounds  of  chloride  of  lime.  It  will  be  seen  from  the 
nature  of  the  charge  that  the  chlorine  is  generated  in  the  barrels 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.         21 

themselves,  and  attacks  the  gold  while  in  a  nascent  state.*  In  order 
to  make  the  charges  uniform,  the  ore  is  mixed  so  as  to  yield  4  to  5 
ounces  per  ton.f 

The  chlorination-barrels  have  been  much  altered  from  time  to 
time.  They  are  now  made  at  the  mine  out  of  the  native  timber 
(Eucalyptus),  the  staves  being  made  of  " spotted  gum"  and  the  ends 
of  "iron  bark/7  with  an  inside  diameter  of  3  feet  6  inches.  A  cast- 
iron  frame  was  at  one  time  pla'ced  round  the  outside  edges.  The 
barrels  are  tarred  to  render  them  tight  and  are  protected  inside  by 
a  double  lining,  an  innermost  wooden  lining  protecting  the  lead  one. 
They  revolve  on  horizontal  bearings,  the  power  being  supplied  by  a 
belt  travelling  around  the  barrel  itself.  Six  revolutions  per  minute 
is  the  usual  speed,  and  the  charge  is  removed  after  an  interval  of 
from  1J  to  2  hours. 

The  barrels  discharge  into  84  leaching-tubs.  These  tubs  or  vats 
will  hold  2J  to  3  tons  of  pulp  each,  and  are  supplied  with  filter-beds 
of  sand  and  gravel,  through  which  the  solution  passes  before  it  is 
conducted  by  lead  and  antimony  pipes  to  the  charcoal-filters.  These 
are  64  in  number,  V-shaped  and  packed  with  2  feet  of  charcoal  of 
unusual  fineness,  the  upper  layers  having  the  size  of  coarse  blasting- 
powder,  and  increasing  in  fineness  toward  the  bottom.  From  9  to  14 
bushels  are  used  in  each  filter. 

When  saturated  with  the  precipitated  gold  the  charcoal  is  removed 
to  the  assay-office,  where  it  is  burned  to  an  ash  containing  75  per 
cent,  of  metallic  gold.  The  solution  from  the  filters  passes  into 
tanks  of  concrete,  whence  it  is  pumped  back  to  be  used  again  in 
the  chlorination-barrels. 

The  sulphuric  acid  used  in  the  generation  of  the  chlorine  is  manu- 
factured upon  the  ground  in  leaden  chambers,  having  a  capacity  of 
20  tons  per  week.  It  is  estimated  that  by  the  production  of  the 
acid  on  its  own  premises  the  company  saves  £20,000  per  annum. 
There  are  also  extensive  work-shops,  with  lathes  and  shearing- 
machines,  together  with  two  assay-offices,  well  equipped  with  all  the 
necessary  appliances.  The  whole  plant  is  run  continuously,  being 
lit  by  electricity  at  night,  when  the  mountain  assumes  a  very  beau- 
tiful and  animated  appearance. 

The  mine  and   all  its  surroundings  bear  testimony  to  the  great 


*  After  the  style  of  the  processes  patented  by  Mears  in  1877  and  De  Lacy  in  1864. 
f  The  pleasure  of  producing  a  uniform  mixture  of  such  high  grade  has  not  been 
possible  since  the  time  of  my  visit. 


22 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND. 


energy  displayed  in  its  development,  in  keeping  with  the  value  and 

size  of  the  great  ore-deposit  which  has  made  Mount  Morgan  famous. 

The  accompanying  plate,  made  from  a  photograph,  gives  a  good 


idea  of  the  surroundings  of  the  mine.  In  the  foreground  is  the 
bridge  crossing  the  Dee  creek  ;  immediately  above  is  the  old  stamp- 
mill;  behind  it  is  a  pile  of  the  ore  first  broken;  and  behind  that 


THE  MOUNT  MORGAN  MINE,  QUEENSLAND.         23 

again  are  the  lower  assay-offices.  To  the  left  are  the  old  chlorina- 
tion-works,  while  the  upper  chimney  indicates  the  new  works.  Be- 
yond is  the  Mount  itself,  the  white  spot  being  the  iron  roof  of  the 
main  shoot  which  leads  from  the  upper  workings. 

NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors, 
or  communications  for  publication  as  "  Discussion,"  or  independent 
papers  on  the  same  or  a  related  subject,  are  earnestly  invited. 


II- 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


THE  LIMITATIONS  OF  THE  GOLD  STAMP-MILL. 

BY  T.    A.    RICKARD,    DENVER,    COLORADO. 

(Chicago  Meeting,  being  part  of  the  International  Engineering  Congress,  August,  1893.) 

MILLING  is  one  of  the  metallurgical  arts  whereby  the  extraction 
of  the  largest  possible  proportion  of  the  value  in  an  ore  is  effected 
at  the  least  possible  expense.  Stamp-milling*  is  that  particular 
process  in  which  a  heavy  body  of  iron  is  caused  to  fall  upon  the  ore 
so  as  to  disintegrate  it  and  thereby  induce  a  separation  between  what 
is  valuable  and  what  is  worthless.  The  latter  is  usually  less  in 
specific  gravity,  and  is  therefore,  by  the  further  aid  of  water,  removed 
from  the  former,  which  is  then  collected  by  the  use  of  mercury. 

Several  similes  have  been  employed  to  describe  this  process.  The 
stamp  has  been  likened  to  a  hammer  of  which  the  stem  is  the  handle 
and  the  die  the  anvil.  The  ore  upon  which  the  stamp  falls  has  been 
compared  to  a  nut  awaiting  the  descent  of  the  hammer  whose  blow 
is  to  separate  the  valueless  shell,  the  quartz,  from  the  valuable  kernel, 
the  gold. 

When  we  begin  to  pursue  our  inquiries,  however,  we  find  that  the 
analogy  is  just  sufficiently  true  to  emphasize  the  departures  from  it. 
The  hammer  falls,  the  anvil  is  fixed  ;  so  with  the  stamps  and  the 
mortar.  The  anvil  is  made  of  softer  metal  than  the  hammer ;  so 
also  the  die  is  often,  and  should  be  always,  of  steel  or  iron  less  hard 
and  more  tough  than  that  of  the  shoe.  The  movement  of  the 
hammer  and  the  drop  of  the  stamp  are  both  intermittent. 

In  regard  to  their  intermittent  action,  as  in  many  other  respects, 
stamp-mills  arrange  themselves  under  two  types,  which,  though  ap- 
parently contradictory,  have  both  been  evolved  from  a  common  origi- 
nal, and  are  united  by  a  great  variety  of  intermediate  modifications. 
The  slow  speed  and  the  high  drop  of  the  mills  of  Gilpin  county, 
Colorado,  appear  to  have  very  little  in  common  with  the  fast  speed 
and  short  drop  of  those  of  the  main  gold  belt  of  California;  yet 
the  practice  of  the  one  was  largely  derived  from  that  of  the  other, 

*  I  shall  confine  the  discussion  to  simple  gold  stamp-milling. 


2  LIMITATIONS   OF   THE   GOLD   STAMP-MILL. 

and  each  has  been  adapted  to  the  treatment  of  the  ores  of  its  par- 
ticular region. 

The  first  and  most  apparent  difference  is  that  of  speed.  In  Colo- 
rado the  drop  is  regulated  at  30  per  minute,  while  in  California 
it  averages  from  90  to  105.  The  more  rapid  drop  gives  a  less  in- 
termittent action,  and  in  this  respect  more  nearly  approaches  the 
ideal  machine. 

The  work  done  by  the  hammer  is,  however,  dependent  not  only 
on  the  rapidity  of  its  blows  but  also  upon  its  weight  and  the  distance 
through  which  it  falls.  Keeping  to  the  two  types,  which  we  have 
chosen  as  representatives  of  the  two  systems  of  milling,  we  find  that 
in  Colorado  the  stamp  weighs  550  to  600  pounds  and  falls  a  height 
of  18  to  20  inches,  while  in  California  the  stamp  weighs  from  750 
to  850  pounds  and  drops  only  4  to  6  inches.  Upon  multiplication 
of  these  three  factors — weight,  drop,  and  speed — we  find  that  the 
theoretical  work  done  is  nearly  equal  and  is  about  one  horse-power. 

In  milling,  however,  the  efficiency  of  the  stamp  as  a  crushing 
machine  is  gauged  by  the  quantity  of  ore  which  it  can  reduce,  and 
we  find  that  this  does  not  at  all  correspond  to  the  theoretical  equality 
of  the  mills.  In  Colorado  the  stamp  crushes  1  ton  per  twenty-four 
hours,  while  in  California,  with  an  ore  of  similar  hardness,  the 
amount  is  from  .two  and  a  half  to  three  times  as  much.  Why  is  this 
difference?  To  explain  it  we  must  suppose  the  hammer  to  fall  not 
upon  the  dry  and  wide  surface  of  an  anvil,  but  upon  a  face  of  iron 
confined  within  a  narrow  box  and  under  water.  This  box  corre- 
sponds to  the  mortar  or  coffer  of  the  stamps.  It  has  no  opening* 
save  in  front,  where  a  metallic  grating  or  screen  permits  the  escape 
of  only  that  part  of  the  material  which  has  been  crushed  sufficiently 
small  to  pass  through  the  openings.  The  ore  upon  the  die  is 
under  water.  The  depth  of  that  water  depends  upon  the  level 
of  the  bottom  of  the  aperture  occupied  by  the  screen-frame.  In 
Colorado  the  depth  of  discharge,  as  measured  by  the  distance  from 
the  bottom  of  the  screen  to  the  top  of  the  die,  is  14  inches,  but 
in  California  it  is  4  inches  only.f  Herein  lies  the  key  to  the  differ- 
ence in  the  crushing  capacity  of  the  two  mills.  Though  the  same 
amount  of  power  be  expended,  and  though  the  screen  used  be  of 
similar  mesh,  yet  in  the  Colorado  mill  the  stamp  falls  through  10 


*  The  feed-hole  is  higher  up  and  does  not  concern  us  here. 

f  In  making  the  comparison  between  the  two  systems  of  milling,  I  have  pur- 
posely chosen  extreme  types. 


LIMITATIONS   OF   THE   GOLD   STAMP-MILL.  3 

inches  more  of  water  and  has  to  discharge  the  pulp  at  a  level  10 
inches  higher  than  in  the  California  mill.  The  greater  depth  of 
discharge  deadens  the  effectiveness  of  the  blow  of  the  stamp  and 
weakens  the  force ^of  the  splash.  Another  result  is  obtained.  While 
the  screen  does  not  in  either  case  succeed  in  sizing  the  material  dis- 
charged through  it,  yet  it  will  be  found  that,  though  provided  with 
similar  screens,  the  pulp  issuing  from  the  deep  mortar  has  a  fineness 
much  greater  than  that  discharged  by  the  shallow  one.  The  pulver- 
ized ore  is  retained  by  the  deep  mortar  long  after  its  particles  have 
been  crushed  to  a  size  permitting  their  passage  through  the  screen- 
openings,  and  they  therefore  become  repulverized  to  a  further  degree 
of  fineness. 

This  touches  upon  one  of  the  points  in  respect  of  which  the  stamp- 
mi  11  is  most  faulty.  By  actual  test  it  is  found  that,  though  using  a 
40-mesh  screen,  for  instance,  with  the  theoretieal  supposition  of 
crushing  to  that  particular  size,  yet  in  a  Colorado  ifcill  fully  70  per 
cent,  of  the  pulp,  and  in  a  California  battery  about  50  per  cent.,  will 
pass  through  a  100-mesh  sieve.  The  percentage  varies  with  the 
character  of  the  ore,  but  these  figures  may  be  considered  fairly  rep- 
resentative. Two  causes  are  chiefly  responsible  for  this.  The  most 
important  in  its  effects  is  the  pause  which  occurs  between  the  succes- 
sive drops  of  the  stamp.  In  a  Colorado  mill  the  interval  is  two 
seconds;  in  California  it  varies  from  three-fifths  to  two  thirds  of 
a  second.  Particles  of  ore,  which  have  been  pulverized  to  a  fineness 
which  would  permit  of  their  exit  through  the  screen,  are  enabled  to 
settle  towards  the  bottom  of  the  mortar.  It  would  be  expected  that 
the  heavy  metallic  minerals  occurring  in  the  ore  would,  because  of 
their  greater  specific  gravity,  be  most  affected  by  this  feature  of  the 
treatment.  In  practice  this  is  found  to  be  so.  The  fine  slimes  con- 
tain a  large  proportion  of  metallic  sulphides,  generally  valuable  on 
account  of  their  close  association  with  the  precious  metals,  while  the 
coarsest  particles  to  be  found  in  the  tailings  usually  consist  of  quartz 
and  other  minerals  forming  the  less  heavy  gangue. 

The  want  of  any  proper  control  over  the  regular  sizing  of  the 
pulp  is  also  due  to  the  unequal  and  irregular  splash  of  the  water  in 
the  battery  and  the  hap-hazanl  way  in  which  the  particles  of  pulver- 
ized ore  strike  against  the  screen.  In  the  case  of  any  single  particle, 
for  instance,  it  is  a  question  of  hit-or-rniss  whether  it  be  thrown 
against  an  opening  or  a  blank.  If  it  fail  to  pass  through,  it  is 
thrown  back  by  the  recession  of  the  water  and  undergoes  a  further 
agitation  and  probable  pulverization. 


4  LIMITATIONS   OF   THE   GOLD    STAMP-MILL. 

In  practice  this  feature  of  the  stamp-mill  is  recognized  by  both 
the  California  and  the  Colorado  rnillman.  On  the  Pacific  coast  the 
mortars  are  made  narrow,  thereby  diminishing  the  opportunities  for 
the  settling  of  the  particles  of  ore,  and,  by  increasing  the  force  of 
the  splash,  adding  to  the  chances  of  its  exit  through  the  screen.  In 
late  years  there  has  also  been  a  tendency  to  use  wire-cloth  in  place 
of  punched  iron,  for  the  reason  that  the  former,  though  having 
openings  of  identical  size,  yet  has  more  of  them  per  square  inch 
than  the  latter,  and,  therefore,  presents  a  greater  area  of  discharge. 
By  giving  an  inclination  of  10  degrees  to  the  screen-frame,  the  exit 
of  the  pulp  is  further  assisted. 

In  Colorado,  this  defect  of  the  stamp-mill  has  been  utilized, 
and  has  been  made  an  assistant  to  the  millman.  The  mortars  of 
this  district  are  wide  and  roomy,  the  splash  of  the  water  inside  the 
battery  is  weak,  and  the  pulp  remains  inside  until  pulverized  to 
a  fineness  mticH^gxceeding  that  required  foi  its  passage  through  the 
screen.  There  is  a  reason  for  this  apparently  contradictory  feature 
of  the  milling  practice.  To  explain  it  we  must  glance  at  the  ore. 
We  find  it  to  contain  an  average  of  15  per  cent,  of  pyrite.  The 
gold  is  very  fine  and  intimately  associated  with  the  pyrite.  To 
separate  them  it  is  necessary  not  only  to  crush  to  a  certain  degree  of 
fineness,  but  also  to  obtain  conditions  which  will-  permit  the  gold 
when  once  separated  to  settle  upon  amalgamated  plates  placed  in- 
side. The  deep  discharge  causes  the  pyrite  to  remain  in  the  mortar- 
box  long  after  it  has  been  pulverized  to  a  size  smaller  than  the 
screen-openings;  the  long  drop  gives  the  interval  of  time  required 
to  allow  of  the  settling  of  the  fine  gold,  while  the  roomy  character 
of  the  mortar  aids  the  deep  discharge  in  affording  a  chance  for  the 
gold  to  get  out  of  the  way  of  the  falling  stamps  and  to  become 
amalgamated  upon  the  two  copper  plates  inserted  at  the  back  and 
front  of  the  mortar.  In  this  way  about  two-thirds  of  the  total  yield 
of  amalgam  is  obtained  inside  the  mortar.  In  California  the 
introduction  of  plates  is  not  admissible,  in  rnortars  having  so  shal- 
low a  discharge  as  4  inches,  because  the  more  constant  and  more 
violent  agitation  of  the  pulp  prevents  the  settlement  of  the  gold 
and  would  cause  the  abrasion  or  "scouring"  of  the  surface  of 
amalgamated  plates.  A  certain  varying  percentage  of  gold  is, 
indeed,  usually  arrested  inside,  partly  by  the  aid  of  mercury 
added  to  the  ore  as  it  is  fed  into  the  battery,  but  this  is  of  such 
a  coarseness  that  gravity  alone  would  serve  to  keep  it  within  the 
mortar. 


LIMITATIONS   OF   THE   GOLD   STAMP-MILL.  5 

We  have  now  entered  into  the  discussion  of  the  effects  produced 
by  the  action  of  the  stamp  upon  the  ore.  In  many  respects  it  de- 
parts from  the  analogy  of  the  hammer  which  cracks  open  a  nut. 
While  being  lifted  the  stamp  also  turns.  This  is  effected  by  the 
friction  of  the  cam-surface  against  the  under  side  of  the  tappet.  In 
a  slow-drop  mill  the  stamp  makes  a  complete  turn  each  time  it  is 
lifted,  but  with  an  increased  speed  this  action  is  more  uncertain  and 
from  4  to  10  drops  are  required  to  make  a  whole  revolution. 

This  feature  of  the  stamp-mill  breaks  the  analogy  to  the  hammer 
and  anvil,  and  causes  it  to  resemble  the  pestle  and  mortar.  The 
turning  of  the  stamp  in  rising  is  communicated  to  the  ore  when  it 
falls  and  induces  a  grinding-action,  which  has  important  results. 
The  mere  impact  of  the  stamp  upon  the  particles  of  gold  has  the 
effect  of  hammering  it,  of  increasing  its  density  and  of  preventing 
its  amalgamation,  while  the  turning  of  the  shoe  upon  the  die  causes 
the  abrasion  of  the  surface  of  the  gold  and  the  rubbing  off  of  any 
film  of  foreign  matter,  which,  by  preventing  contact  between  the 
gold  and  the  mercury  is  prejudicial  to  amalgamation.  In  grinding 
the  ore  the  stamp,  however,  also  tends  to  convert  it  into  slime.  The 
hammer  which  cracks  open  the  nut  liberates  the  kernel  without 
smashing  it,  but  in  pursuing  the  simile  we  find  that  the  stamp  not 
only  breaks  the  shell,  but  both  the  kernel  and  the  shell  are  further 
crushed,  and  their  particles  become  confused  together.  The  stamp 
which  frees  the  gold  from  the  quartz  has  to  deal  with  a  material  in 
which  the  valuable  and  the  valueless  constituents  are  so  uneven  in 
size  and  so  intermixed  that  the  one  is  often  crushed  too  much  and 
the  other  too  little. 

I  have  seen  auriferous  quartz*  which  very  nearly  approached  our 
simile  of  the  nut.  The  gold  occurred  in  seams  and  cavities  in  a 
quartz  which  had  a  honeycombed  character.  With  such  an  ore 
there  is  just  a  certain  blow  which  will  break  the  brittle  quartz  and 
liberate  the  ductile  gold.  Such  ideal  conditions  are  very  rare.  The 
different  parts  of  the  same  ore  usually  vary  both  in  hardness  and 
composition.  The  same  work  done  on  two  pieces  of  mill-stuff  will 
produce  entirely  dissimilar  results.  In  the  stamp-battery  the  heavy 
sulphide  minerals  are  pulverized  to  a  greater  fineness  than  the  si- 
liceous gangue.  When  the  gold  is  not  too  closely  associated  with  the 
pyrite,  coarse  and  rapid  crushing  will  produce  an  adequate  separa- 
tion; but  when  the  metal  is  in  a  finely  divided  condition  and  very 

*  At  Clunes,  Victoria,  Australia. 


6  LIMITATIONS   OF   THE   GOLD   STAMP-MILL. 

intimately  mixed  with  the  pyrite,  then  fine  crushing  is  demanded 
and  can,  unfortunately,  only  be  obtained  by  the  production  of  a  very 
undesirable  excess  of  slimes. 

We  have  glanced  at  the  results  produced  by  the  turn  of  the  stamp 
upon  the  ore.  Upon  the  mechanism  itself  the  results  are  beneficial. 
The  revolution  of  the  stamp  equalizes  the  wear  upon  the  shoes  and 
dies.  It  tends,  also,  by  maintaining  an  even  crushing-surface,  to 
prevent  that  decrease  of  efficiency  which  occurs  when  either  hammer 
or  anvil  has  an  irregular  face. 

Water  is  the  vehicle  used  for  the  removal  of  the  valueless  por- 
tions of  the  ore  from  those  which  are  valuable.  Its  low  specific 
gravity  as  compared  to  both  the  metal  and  its  enclosing  gangue  en- 
ables us  to  use  it  as  a  medium  for  their  separation.  A  liquid 
having  a  specific  gravity  greater  than  that  of  water,  and  interme- 
diate between  that  of  the  gold  and  its  gangue,  would  be  more  effec- 
tive if  its  use  were  practicable,  which  it  is  not. 

In  the  mill,  however,  specific  gravity  is  not  the  only  factor  we 
have  to  consider.  The  water  discharged  from  a  stamp-mill  often 
transports  the  heavy  pyrite  further  than  the  light  quartz.  This  is 
due  to  the  fact,  already  referred  to,  that  the  pyrite  remains  inside 
the  mortar  longer  than  the  quartz  and  becomes  pulverized  to  a 
further  degree  of  fineness.  It,  therefore,  presents  a  larger  surface 
to  the  water.  Again,  the  metallic  sulphides  commonly  occurring  in 
gold  ores  have  a  cleavage  more  highly  developed  than  that  of  quartz ; 
therefore,  while  the  latter  finds  its  way  into  the  water  in  irregular 
and  angular  grains,  the  former  will  be  found  in  thin  plates  and 
flakes,  which  readily  float  upon  a  running  stream. 

Water  is  the  fluid  used,  but  air  also  plays  its  part.  During  the 
time  of  its  violent  agitation  under  the  falling  stamp,  the  water  en- 
tangles a  certain  amount  of  air.  Such  air  exists  in  the  form  of 
small  bubbles  which  hold  the  finely-pulverized  ore  in  suspension 
and  thus  become  the  main  agent  in  the  floating  of  the  slimes. 
Warmth  causes  the  air  to  expand  and  the  bubbles  to  become  dis- 
sipated ;  therefore  any  rise  in  the  temperature  of  the  water,  such, 
even,  as  is  caused  by  the  impact  between  the  stamps  and  the  ore 
upon  the  die,  is  favorable  to  a  diminution  in  the  amount  of 
slime. 

When  the  pulp  is  discharged  from  the  mortar-box  it  runs  down 
copper  plates  covering  long  sloping  tables.  The  copper,  whether 
plain  or  silver-plated,  is  provided  with  an  amalgamated  surface, 
and  it  is  this  amalgamated  surface  which  is  supposed  to  do  the 


LIMITATIONS    OF   THE   GOLD   STAMP-MILL.  7 

work  of  arresting  the  gold.  Mercury  unites  with  gold  forming  a 
heavy  amalgam;  hut,  in  practice,  it  is  found  that  a  plate  which  is 
covered  with  a  good  coating  of  gold-amalgam  will  serve  to  arrest 
gold  much  more  effectually  than  a  clean  surface  of  either  amalga- 
mated silver  or  copper. 

The  amalgamating-tahles  have  a  slope  varying  with  the  amount 
of  water  used,  the  heaviness  of  the  pulp,  and  the  rapidity  of  the 
crushing.  A  gradient  of  |-inch  per  foot  is  common  in  Australia, 
while  in  Colorado  the  inclination  is  over  2  inches  per  foot.*  The 
colonial  mills  consume  5  gallons  of  water  per  stamp  per  minute, 
while  those  of  Colorado  use  less  than  2  gallons.  Theoretically,  the  use 
of  the  least  possible  quantity  of  water,  and  the  spreading  of  the  pulp 
over  the  largest  possible  surface,  will  give  the  best  separation  of  the 
gold  from  the  gangue.  In  practice,  the  varying  composition  of  the 
ore  prevents  a  nice  adjustment  of  the  conditions.  You  may  readily 
determine  an  inclination  which  will  be  most  effective  in  causing  a 
separation  of  the  gold  from  the  quartz,  but,  it  may  be  such  as  to 
cause  the  pyrite  to  settle.  On  the  other  hand,  the  slope  may  be  so 
adjusted  that  the  pyrite  is  carried  away ;  but,  such  conditions  may 
then  be  obtained  as  will  also  permit  of  the  escape  of  the  gold. 

The  amalgamating-tables  are  attached  to  the  frame-work  of  the 
mill.  The  vibration  set  up  by  the  falling  stamps  causes  a  pulsation 
of  the  water  flowing  over  the  plates  similar,  in  a  way,  to  the  action 
of  a  jig.  This  assists  the  work  of  gravitation.  The  vibration  has, 
however,  another  effect,  namely,  that  of  crystallizing  the  iron  of  the 
working  parts  of  the  mill,  making  them  brittle  and  decreasing  their 
time  of  service.  In  this,  as  in  other  respects,  the  stamp-mill  presents 
contradictory  features. 

At  the  outset,  we  described  milling  as  the  art  of  treating  an  ore 
so  as  to  extract  the  maximum  of  value  at  the  minimum  of  expense. 
Let  us  apply  the  description  to  the  two  types  of  mill  to  which  par- 
ticular reference  has  been  made.  In  Colorado,  a  stamp  crushes  1 
ton  of  the  ore  of  the  Gilpin  county  mines  in  24  hours,  and  the  cost, 
using  free  water  power,  is  70  cents.  In  California,  the  best 
equipped  large  mills  crush  at  the  rate  of  rather  more  than  2J  tons 
at  a  cost,  also  using  free  water  power,  of  about  35  cents  per  ton. 
The  extraction  in  both  regions  will  be,  by  amalgamation  alone,  about 
70  per  cent.  We  will  omit  the  amount  extracted  by  the  concentration 
of  any  valuable  pyrite,  because  the  percentage  of  such  material  is 

*  An  Australian  mill  usually  crushes  2  tons  per  stamp  per  24  hours. 


8  LIMITATIONS    OF   THE   GOLD   STAMP-MILL. 

very  variable,  and  it  forms  a  by-product,  the  value  of  which  depends 
largely  upon  local  conditions. 

The  ore  of  the  Gilpin  county  mines  carries  about  15  per  cent,  of 
pyrite,  and  other  heavy  sulphides.  The  gangue  is  more  feldspathic 
than  quartzose,  and  is  the  product  of  the  alteration  of  the  country- 
rock — granitoid  gneiss — and  of  the  dikes*  which  penetrate  it.  The 
gold  is  not  only  present  in  a  state  of  very  fine  subdivision,  but  it  is 
also  intimately  associated  with  the  pyrite. 

On  the  other  hand,  the  mill-stuff  treated  in  Amador,  Calaveras 
and  Tuolumne  carries  from  1  to  2  per  cent,  of  pyrite.  The  gangue 
is  quartz,  but  the  ore  also  contains  a  very  large  proportion  of  the 
country-rock,  which  in  this  case  is  slate,  augite  schist,  and  diabase. 
Of  these,  slate  predominates.  The  gold  is  coarser  than  that  of  the 
Colorado  ore,  and  it  is  not  so  closely  associated  with  the  pyrite. 

Let  us  now  consider  the  results  to  be  obtained  by  an  interchange 
of  treatment,  using  California  batteries  on  Colorado  ore,  and  vice 
versa,  f  The  Gilpin  county  ore  is  of  medium  grade,  say  8  dwts.,  or 
$8  per  ton.  The  local  methods  extract  $5.60J  at  a  cost  of  70  cents. 
A  California  mill  would  give  an  extraction  of  only  $4,  but  would 
crush  such  soft  ore  fully  three  times  as  fast,  so  that  the  cost  would 
be,  say  25  cents,  giving  a  net  yield  of  $3.75  as  against  $4.90  obtained 
by  the  methods  of  the  district.  Here,  the  slower  mill  gives  the 
best  results  with  a  particular  ore,  and  the  Colorado  mill  man  con- 
siders the  California!!  very  stupid  because  he  does  not  use  Colorado 
methods.  Let  us  go  to  California  and  use  the  Gilpin  county  mill 
upon  an  ore  of  simpler  character  and  of  lower  tenor.  We  will  con- 
sider the  treatment  of  an  ore.  containing  6  dwts.,  or  worth  $6  per 
ton.  The  California  mill  would  extract  70  per  cent,  at  a  cost  of 
35  cents,  leaving  a  balance  of  $3.95  per  ton.  The  Colorado  battery 
would  extract  an  increased  percentage,  say  75  per  cent.,  but  the  ore 
being  much  harder  than  that  of  Gilpin  county,  the  crushing  capacity 
would  be  less  and  the  cost  per  ton  greater  than  when  treating  Gilpin 
county  ore,  say,  therefore,  $1.00  per  ton,  leaving  a  net  yield  of  $3.50 
per  ton.  The  California  mill,  if  crushing  100  tons  of  ore  per  day, 
would,  therefore,  show  a  profit  $45  per  day  greater  than  that  of  the 
Colorado  mill.  As  a  matter  of  fact,  there  are  other  practical  con- 
siderations which  would  render  inadvisable  the  interchange  of 

*  The  "porphyry"  of  the  miners;  really,  quartz-andesite. 

f  In  making  the  comparison  the  cost  of  motive  power,  being  very  variable,  is 
left  out  of  the  count. 

J  Amalgamation  only,  omitting  concentration  afterward,  is  here  included. 


LIMITATIONS   OF   THE   GOLD   STAMP-MILL.  9 

methods,  among  which  may  be  mentioned  the  smaller  size  of  the 
ore-bodies  of  Gilpin  as  compared  to  those  of  California;  while  it  must 
also  be  remembered  that  the  construction  of  a  Colorado  mill  of  a 
capacity  equal  to  that  of  a  California  plant  would  require  twice  as 
much  capital. 

The  comparison  just  made  will  serve  as  an  illustration  of  the 
fact  that  milling  is  a  business  for  getting  money,  and  not  a  scientific 
pursuit  directed  to  the  obtaining  of  a  perfect  metallurgical  treat- 
ment. 

The  contrast  between  the  methods  in  use  in  two  mining  districts 
in  the  same  country,  illustrates  the  first  axiom  of  all  successful  ore- 
reduction,  namely,  that  the  treatment  must  be  suited  to  the  char- 
acter of  the  ore.  Colorado  methods  in  California  would  probably 
fail  just  as  surely  as  California  ways  have  been  unsuccessful  in 
Gilpin  county.  This  is  a  truism  not  always  remembered  by  ma- 
chinery firms,  who  do  not  desire  to  be  bothered  by  the  making  of 
new  patterns.  Too  often,  the  ore  is  required  to  bend  to  a  certain 
treatment  in  a  mill  of  a  particular  design,  instead  of  the  mill  being 
modified  to  suit  the  necessities  of  a  particular  ore. 

The  stamp-mill  has  presented  to  us  many  contradictory  features. 
It  is  seen  to  be  compounded  of  good  and  ill.  It  may  be  simple,  but 
it  is  clumsy ;  it  may  be  crude,  but  it  is  effective.  As  a  machine,  it 
has  undergone  an  evolution  common  to  all  human  inventions.  It 
was  founded  on  the  first  stone  implement  of  the  prehistoric  savage; 
it  became  modified  into  the  matate  of  the  Mexican  and  the  tilt- 
hammer*  of  the  Chinese ;  it  progressed  until  running  water  was 
called  in  to  aid  human  muscle,  and  in  the  machine  of  the  Hun- 
garian peasant,  it  reached  the  primitive  type  from  which  our 
present  mills  were  evolved.  How  great  has  been  the  comparatively 
recent  improvement  can  be  seen  by  stepping  from  Hungary  to  Cali- 
fornia. 

In  the  valleys  around  Verospotak,  in  Transylvania,  the  larger 
mills f  consist  of  twelve  stamps,  in  coffers  holding  four  each.  The 
power  is  derived  from  an  overshot  water-wheel  10  feet  in  diameter. 
The  cam-shaft  is  of  iron,  and  revolves  on  agate  bearings,  lubricated 
with  water.  The  lifter,  or  cam,  is  iron-shod.  The  stamp  weighs 
250  pounds,  and  has  an  agate  head.  The  stem,  the  coffer,  and  all 

*  "  A  Chinese  System  of  Gold-Milling,"  by  Henry  Louis,  Trans.,  xx.,  324. 

f  Modern  American  mills  have  been  lately  introduced,  and  can  be  seen  working 
side  by  side  with  those  dating  back  to  100  A.D.  For  the  particulars  above  given, 
I  am  indebted  to  Mr.  E.  H.  Liveing. 


10 


LIMITATIONS    OF   THE   GOLD   STAMP-MILL. 


LIMITATIONS   OF   THE   GOLD  STAMP-MILL.  11 

the  rest,  are  made  of  beechwood.  Each  stamp  drops  30  times  per 
minute,  and  crushes  about  300  pounds  of  soft  ore  per  24  hours. 
These  machines  have  changed  but  little  since  the  time  of  the  Roman 
occupation  under  Trajan,  when  this  district  was  a  part  of  the  province 
of  Dacia.* 

Let  us  now  go  to  California,  whose  record  is  little  more  than  the 
record  of  a  generation.  Among  the  foothills  of  the  Sierra  Nevada 
we  find  mills  containing  80  stamps,  weighing  750  to  850  pounds 
each,  and  dropping  95  times  per  minute.  Those  of  the  working 
parts  which  are  not  of  iron  are  made  of  steel.  At  single  mills,  200 
tons  of  ore  are  crushed  per  day.  The  mill  building  has  a  height 
of  70  feet,  and  the  ore  is  never  touched  by  manual  labor  from  the 
moment  that  it  arrives  at  the  top  in  the  mine-cars  to  the  time  when 
it  is  discharged  at  the  bottom  as  waste. 

In  Transylvania,  the  individual  shareholder  often  has  his  own 
mill;  in  California  a  thousand  unite  to  operate  one,  which  can,  in 
24  hours,  treat  as  much  ore  as  the  Hungarian  mill  crushes  in  100 
days.  The  little  machine  of  the  Hungarian  has  been  tapping  away 
like  a  woodpecker  for  eighteen  centuries,  and  yet  has  not  produced 
as  much  gold  as  has  been  contributed  in  the  brief  time  of  one  gen- 
eration by  that  completer  mechanism  whose  muffled  thunder  echoes 
among  the  canons  of  California. f 

What  has  been  done  may  serve  as  a  measure  of  what  can  yet  be 
done.  Perfection  is  as  unattainable  in  milling  as  in  any  other  branch 
of  industrial  art ;  otherwise  progress  were  soon  ended.  We  can  com- 
pare the  old  mill  with  the  new,  not  only  with  a  complacent  satisfac- 
tion at  the  advance  that  has  been  made,  but  with  the  consciousness 
that  where  so  much  improvement  was  possible  much  room  for  im- 
provement must  remain. 

It  is  not  for  me  to  attempt  to  foretell  what  place  the  stamp-mill 
is  destined  to  hold  in  the  metallurgy  of  the  future.  Let  me,  however, 
in  concluding,  suggest  the  reflection  that  though  the  appliances  of 
to-day  may  show  a  great  advance  upon  the  older  more  imperfect 
type  from  which  they  were  evolved,  yet  there  is  no  mining  district 
that  possesses  a  mill  which  cannot,  in  some  essential,  be  improved  upon. 

*  Well-preserved  gold  coins  of  the  time  of  Trajan  have  been  found  in  the  mine- 
dumps.  » 

f  The  accompanying  illustration  of  an  old  and  a  new  mill  has  been  engraved 
from  a  pen-and-ink  drawing,  made  by  my  friend,  Mr.  H.  R.  Pridham,  after  a  pho- 
tograph taken  by  myself  during  my  residence  in  California,  some  years  ago.  In 
the  middle  distance  is  an  old  ruined  water-wheel,  formerly  the  motor  of  a  small 
ten-stamp  mill,  the  dismantled  portions  of  which  remain  in  the  shed  on  the  left. 
In  the  background  is  a  fully  equipped,  modern,  California  steam-mill. 


4 

Subject  to  Revision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.) 


THE  GOLD-FIELDS  OF  OTAGO. 

BY  T.  A.  RICKARD,  DENVER,  COLORADO. 

(Plattsburgh  Meeting,  June,  1892,) 

THE  province  of  Otago  consists,  roughly  speaking,  of  the  southern 
half  of  the  South  Island*  of  New  Zealand.  On  three  sides  it  is 
washed  by  the  Pacific  Ocean  and  on  the  north  it  abuts  against  West- 
land  and  Canterbury.  It  covers  an  area  of  over  20,000  square 
miles,  and  for  the  most  part  has  an  extremely  broken  surface ;  the 
narrow  plains  of  the  sea-board  are  bounded  by  the  rounded  foot- 
hills which  in  turn  are  overlooked  by  range  after  range  of  the  snowy 
summits  whose  varied  beauty  has  made  the  island  known  as  the 
Switzerland  of  the  southern  hemisphere. 

The  gold-fields  are  confined  to  the  quartzose  schists  which,  in  a 
broad  band,  70  to  75  miles  wide,  cross  the  district  extending  in  a 
northwesterly  direction  from  the  shore  of  the  western  ocean  into  the 
northern  provinces.  These  quartzose  schists  are  the  characteristic 
rocks  of  Otago,  and  to  their  curious  structure  are  due  the  interesting 
differences  exhibited  by  the  mining  districts  in  the  modes  of  occur- 
rence of  the  gold.  These  rocks,  which  are  almost  unbroken  over 
their  full  extent,  have  been  divided  by  the  Provincial  Geologist,  f 
F.  W.  Hutton,  into  two  series  of  beds,  named  respectively  the 
Wauaka  and  Kakanui  formations.  The  only  reason  given  for  this 
division  is  the  desire  "  to  divide  such  an  enormous  thickness  of  rocks 
in  order  that  the  map  might  display  somewhat  of  the  geological 
structure  of  the  district.''^  As  Hutton  and  others  have  pointed  out 
there  is  in  fact  no  dividing  line.  The  changes  noticeable  in  the 
ascending  series  of  schists  are  very  gradual,  and  are  due  to  the 
slowly  decreasing  effects  of  metarnorphism.  Hutton  estimates  the 
thickness  of  the  Wanaka  series  at  as  much  as  50,000  feet,  and  the 

*  New  Zealand  is  variously  spoken  of  as  consisting  of  the  North,  Middle  and 
South  islands  or  of  the  North,  South  and  Stewart's  Island.  The  last  is  of  insignifi- 
cant size  and  importance.  Otago  is  in  the  southern  of  the  two  chief  islands. 

|  That  is,  the  geologist  of  the  province  of  Otago.  It  is  the  term  used  in  the  gov- 
ernment publications. 

J  Page  33  of  Geology  of  Otago,  1875. 


2  THE   GOLD-FIELDS   OF   OTAGO. 

Kakanui  at  52,800,  or  twenty  miles  for  the  two.  The  information 
obtainable  is  not  sufficient  for  trustworthy  estimates,  but  it  is  certain 
that  these  rocks  have  an  enormous  thickness  over  a  very  large  area. 

•  The  question  of  their  age  is  surrounded  with   much  difficulty. 
The  geologists  of  New  Zealand  are  not  agreed  as  to  either  nomen- 
clature or  chronological   position ;   and   the  maps  of   the   several 
authorities  show  most  unfortunate  divergencies  of  opinion.     For  our 
immediate  purpose  it  may  suffice  to  say  that  the  quartzose  schists  of 
Otago  overlie  the  syenitic  gneiss  and   granite,  which  Hector  and 
Hutton  agree  in  regarding  as  pre-Silurian  ;*  while  they  underlie  a 
are  overlain  by  those  of  the  Matai,  the  geological  position  of  which 
was  for  a  long  time  sharply  debated,  but  has  been  determined  by 
fossils  as  Carboniferous.     Such  is  the  evidence  upon   which  the 
quartzose  schists  have  been  labelled  Silurian. 

The  rocks  themselves  have  been  variously  described  as  phyllite, 
clay-slate,  mica-schist,  etc.  Hornblende-schist  and  quartzite  are 
also  known  to  occur.  The  mineral  constituents  are  subject  to  fre- 
quent variation.  The  name  "  phyllite  "  is  often  used,  but  since  the 
argillaceous  character  of  the  mica-schist  has  been  seldom  more  than 
guessed  at,  this  usage  may  be  taken  as  a  mere  fa§on  de  parler. 
Neither  of  the  above  names  describes  distinctively  the  rock  which 
forms  the  prevailing  type,  and  I  would  suggest  "quartzose  mica- 
schist,"  or,  for  brevity,  "  quartzose  schist "  as  being  more  descriptive. 

The  most  striking — and  at  times  a  very  remarkable — feature  of 
the  schists  of  Otago  is  the  extraordinary  development  of  quartz.  In 
many  localities  (for  instance,  in  the  twelve  miles  between  Lawrence 
and  Waipori,  where  the  road-cuttings  afford  numerous  sections)  the 
quartz  forms  half  the  bulk  of  the  rock.  It  is  interbedded  among 
the  folia  of  the  schist,  often  in  very  regular  and  continuous  lines. 
The  seams  of  the  quartz  will,  over  a  wide  area,  have  an  average 
thickness  of  from  half  an  inch  to  an  inch,  increasing  often  to  bands 
5  or  6  inches  wide.J  Fig.  1  illustrates  an  outcrop  of  such  quartz- 
banded  rock. 

It  is  noteworthy  that  over  the  greater  part  of  the  gold-fields  the 

*  Sir  James  Hector  calls  the  granite  pre-Silurian,  and  F.  W.  Hutton  has  called 
the  formation  by  the  name  of  Manipori,  and  considers  it  Lanrentian  or  Cambrian, 
series  of  rocks  called  Devonian  and  Carboniferous,f  which  in  turn 

f  Je  Anau  series  (Devonian)  of  Hector  or  the  Kaikora  formation  (Carboni- 
ferous) of  Hutton. 

t  Above  La  Grave,  Hautes  Alpes,  I  have  seen  sections  in  the  Lias  which  strongly 
reminded  me  of  this  feature  of  the  Otago  schists. 


THE   GOLD-FIELDS   OF  OTAGO.  3 

beds  preserve  a  very  flat  dip  over  very  wide  areas  and  are  rarely, 
and  only  locally,  much  tilted. 

That  the  quartz  is  formed  along  lines  of  bedding,  and  not  cleav- 
age-planes, is  amply  proved  by  the  observation  of  the  changes  in 
the  character,  color  and  composition  of  the  rock,  which  take  place 
at  right  angles  to  the  lines  of  foliation,  whose  low  angle  of  inclina- 
tion is  also  confirmatory,  since  cleavage  is  usually  characterized  by  a 
high  angle. 

The  quartz  is  most  probably  of  secondary  origin,  and  due  to  the 
exudation  of  silica  from  an  extremely  siliceous  silt  and  segregation 
along  the  lines  of  lamination  during  the  period  of  metamorphism. 

To  those  acquainted  with  the  mineral  deposits  of  the  Western 
United  States,  Europe  or  Australia,  the  almost  entire  absence  of 
eruptive  rocks  over  such  a  wide  auriferous  area  will  appear  extra- 
ordinary. It  will  also  largely  explain  the  scarcity  of  lode- forma- 
tions, the  comparative  want  of  definition  which  belongs  to  most  of 
the  veins,  and  the  small  extent  of  the  ore-bodies,  notwithstanding 
the  fact  that  large  portions  of  the  country-rock  are  undoubtedly  in 
themselves  gold-bearing.  To  the  latter  fact  is  due  the  enormous 
quantity  of  alluvium,  the  yield  from  which  is  much  greater  in  im- 
portance than  that  of  the  quartz-veins  of  the  province. 

The  history  of  the  first  discovery  of  gold  in  Otago  has  been  re- 
lated by  one  of  the  pioneers — Vincent  Pyke.  It  may  be  considered 
as  dating  from  the  4th  of  June,  1861,  the  day  upon  which  a  Dune- 
din  newspaper  published  a  letter  from  Gabriel  Reed  announcing  the 
finding  of  gold  at  Tuapeka.* 

Before  that  date,  a  native  of  Bombay,  Edward  Peters,  or  "  Black 
Peter,"  as  he  was  more  generally  known,  had  been  getting  gold  in 
what  was  afterwards  famous  as  Gabriel's  Gully,  the  locality  which 
saw  the  first  great  "  rush  "  of  1861.  In  the  following  year  the 
known  auriferous  area  was  extended  far  into  the  mountains  of  the 
interior,  and  on  August  16, 1862,  Hartley  and  Reilly — a  native-born 
American  and  a  Yankee  Irishman — astonished  Dunedin  by  deposit- 
ing at  the  treasury  a  bag  containing  87  pounds  of  gold.  They  had 
been  quietly  working  on  the  beaches  of  the  Clutha  river  near  the 
Dunstan  gorge,  and  the  announcement  of  their  find  caused  the  then 
small  population  of  Otago  to  make  a  hasty  stampede  into  the  in- 

*  The  first  discovery  of  gold  in  New  Zealand  is  said  to  have  been  made  at  Driv- 
ing Creek,  Coromandel,  in  1852.  The  Coromandel  district  has,  however,  been  over- 
shadowed by  its  neighbor  the  Thames,  which  has  had  a  most  brilliant  though  irregu- 
lar record.  Neither  of  them  has  been  such  a  regular  producer  as  Otago. 


4  THE   GOLD-FIELDS   OF   OTAGO. 

terior.  From  this  time  immigration  from  the  Australian  colonies 
set  in,  and  gold-fields  were  proclaimed*  in  rapid  succession. 

Between  September  and  December,  1862,  70,000  ounces  were  sent 
by  escort  to  Dunedin  from  Dunstan. 

The  working  of  the  gold-deposits  was  rendered  easy  by  the  fact 
that,  unlike  the  wash  of  the  Victorian  fields,  that  of  Tuapeka,  the 
first  Otago  gold-field,  and  those  of  the  province  generally,  contained 
but  little  clay,  and  did  not  necessitate  the  "  puddling  "  which,  at  old 
Bendigo  for  instance,  was  the  treatment  required  by  the  stiff,  hard- 
ened "  cement"  of  the  Australian  alluvium. 

Nuggets  do  not  figure  much  in  the  history  of  the  Otago  gold-fields. 
According  to  Vincent  Pyke  the  largest  was  one  of  27  ounces,  re- 
ported to  have  been  found  at  Waipori  in  1863.  Nuggets  were  com- 
paratively rare,  and  the  few  found  were  very  small,  and  in  no  way 
comparable  to  those  which  in  the  early  "  fifties  "  made  Ballarat  and 
Dunolly  famous. 

The  production  of  Otago  is  shown  in  the  accompanying  statement : 

The  Gold-Production  of  New  Zealand. 


' 

Auckland. 

West  Coast. 

Otago. 

Total." 

Year. 

Oz. 

Value. 

Oz. 

Value. 

Oz. 

Value. 

Oz. 

Value. 

1889 
1890 

28,655 
31,745 

£113,191 
125,760 

101  ,696 
89,096 

£406,451 
356,368 

64,419 
63,410 

£256,430 
255,926 

203,211 
193,193 

£808,549 
773,438 

Highest 
yield, 

886,820* 

1,188,708 

552,572* 

2,140,946 

614,387* 

2,380,750 

735,376* 

2,894,517 

Total 
since  '57, 

1,639,357   6,122,473 
1 

5,093,249 

20,226,540 

4,783,96818,886,928 

11,818,221 

46,425,629 

a.  Including  minor  districts. 

b.  This  was  in  1871,  at  the  time  of  the  Thames  rush. 

c.  Due  to  the  Hokitika  discoveries. 

d.  When  the  Gabriel's  Guliy  Diggings  were  at  their  best. 

e.  In  1871. 

The  mining  industry  of  Otago  at  the  present  time  offers  a  variety 
of  interesting  features.  The  methods  by  which  the  precious  metal 
is  won  are  very  diverse,  including  dredging  and  hydraulic  elevating 
in  addition  to  the  ordinary  forms  of  alluvial  and  deep  mining.  In 
lode-  or  vein-mining — the  "quartz-reefing  "  of  the  colonies — Otago 
is  considerably  behind  its  neighbors  of  the  Australian  continent,  but 


*  When  the  auriferous  character  of  a  district  has  been  proved  the  colonial  gov- 
ernment "  proclaims  "  it  a  gold-field. 


6  THE    GOLD-FIELDS    OF    OTAGO. 

in  alluvial   mining   it  is  first,  and   in   dredging  it  is  the  pioneer. 
We  will  first  consider  the 

LODES. 

One  of  the  oldest  and  best  of  the  gold-fields  is  that  of  Waipori, 
discovered  very  soon  after  Gabriel's  Gully,  which  is  only  10  miles 
distant.  The  most  important  lode  is  that  of  the  "O.  P.  Q."  or 
Otago  Pioneer  Quartz  mine,  which  was  discovered  in  March,  1862, 
by  six  Victorians,  all  Shetland  men,  who  named  it  the  Shetland 
reef.  The  country-rock  is  a  very  fine  silver-green  mica-schist,  with 
an  enormous  proportion  of  interfoliated  quartz.  The  strike  of  the 
lode  is  N.  30°  W.,  and  the  dips  eastward  50°  to  55°,  becoming  more 
flat  in  the  deeper  workings.  The  enclosing  rock  dips  15°  to  20° 
S.  S.  E.,  and  the  lode,  therefore,  cuts  across  it  in  both  strike  and  dip. 
It  traverses  a  low  range  of  hills,  across  whose  brow  the  croppings 
can  readily  be  followed.  The  dimensions  of  the  vein  are  subject  to 
frequent  change ;  indeed,  it  would  be  more  correct  to  consider  the 
quartz  as  occupying  a  line  of  fractured  country  in  which  the  distinc- 
tion between  the  quartz  of  the  surrounding  schists  and  that  of  the 
lode  itself  is  often  obliterated.  The  work  done  has  proved  the  ex- 
istence of  large  irregular  blocks  of  gold-bearing  quartz  of  lenticular 
form,  and  over-lapping  each  other.*  Sometimes  two  or  more  of 
these  blocks  of  ore  may  be  parallel  to  each  other  and  separated  by 
soft. country,  which  near  the  quartz  passes  gradually  into  a  black 
clay  or  fluccan.f  In  this  manner  rich  short  shoots  of  stonej  have 
been  discovered ;  but  the  greater  part  of  the  gold  is  contained  in  the 
country-rock  included  by  the  lode,  that  is,  the  vein-filling,  which  is 
threaded  by  numerous  small  cross- veins,  dying  out  insensibly  among 
the  quartz  seams  of  the  surrounding  schists.  It  would  be  mislead- 
ing to  speak  here  of  foot-  and  hanging- walls  in  the  usual  sense. 
As  a  New  Zealand  miner  would  put  it,  "each  run  of  stone  makes 
its  own  wall."  The  bodies  of  quartz  preserve,  indeed,  a  certain  line, 
which  is  that  of  the  strike  of  the  fissure  or  line  of  fissuring  in  which 
they  have  been  formed ;  but  it  would  be  wrong  to  speak  of  defined 
walls  as  limiting  the  gold-bearing  portion.  The  eastern  boundary — 
the  hanging-wall — of  the  lode  preserves  a  fairly  straight  course,  but 

*  This  recalls  similar  formations  elsewhere.  At  the  Frederick  the  Great  mine, 
Sebastian,  Victoria,  the  ore-shoots  were  of  a  strikingly  similar  character. 

f  Selvage.     The  New  Zealander  calls  it  "  pug." 

J  The  colonial  miner  generally  uses  the  word  "  stone "  instead  of  "  quartz " 
or  "ore." 


THE   GOLD-FIELDS    OF   OTAGO.  7 

there  are  only  suggestions  of  a  foot-wall,  a  series  of  parallel  or  nearly 
parallel  division-planes,  separating  the  quartz  of  the  enclosed  from 
that  of  the  enclosing  schists. 

On  the  Waipori  side  of  the  ridge,  the  lode  traverses  a  portion — a 
bar — of  country-rock  more  siliceous  and  harder  than  usual ;  and  it 
is  to  be  noted  that  within  this  passage  the  quartz  is  barren  of  gold, 
and  contains  a  smaller  amount  of  iron  pyrites  than  in  the  softer  por- 
tions of  the  hill.  In  washing  the  lode-matter,  one  notices  a  heavy 
white  mineral,  which  lingers  with  the  pyrites  and  gold  after  the  rest 
of  the  gangue  has  been  washed  away.  This  is  the  somewhat  rare 
mineral  scheelite  or  tungstate  of  lime,*  which  in  this  district  occurs 
scattered  through  the  schists,  though  rarely  in  workable  quantities. 
In  addition,  the  country-rock  contains  occasional  thin  veins  of  cin- 
nabar, irregular  in  behavior  and  too  small  to  have  economical  im- 
portance. The  presence  of  the  mercury  mineral  is  not  observed  in 
working  the  lodes,  but  it  forms  a  marked  feature  of  the  alluvium  with 
the  gold  of  which  it  is  mixed. 

About  a  third  of  a  mile  westward  is  the  parallel  lode  of  the  Can- 
ton mine,  where  the  true  character  of  the  formation  is  more  readily 
discernible.  Fig.  2  illustrates  the  appearance  of  the  end  of  the 
southeast  drift.  A  A  is  the  "  reef,"  a  vein  of  quartz  which  is  sup- 
posed to  lie  immediately  upon  the  "  foot-wall. "  Along  B  B  the 
country  is  soft,  and  the  included  quartz  folia  are  much  twisted. 
C  C  is  one  of  the  "  false  hanging-walls."  The  whole  width  is  gold- 
bearing,  though  A  A  acts  as  a  guide  in  following  the  auriferous 
channel.  It  is  not  possible  to  say  where  the  "lode"  ends  or  where 
it  begins.  It  is  a  channel  of  country-rock  which  is  auriferous  within 
ill-defined  limits,  and  in  which  the  vein  A  A  acts  as  an  indicator. 
Along  A  A  and  C  C,  it  has  undergone  faulting ;  along  B  B,  distor- 
tion only.  It  is  an  extreme  case  of  what  a  colonial  calls  a  "  mul- 
locky  reef," — a  lode  full  of  mullock  or  waste  rock — a  type  of  ore- 
deposit  more  common  than  is  supposed,  though  the  usual  forms  are 
less  distinct  than  in  this  case.f  We  shall  see  somewhat  of  the  same 
structure  in  the  other  districts  of  the  province. 

*  Specific  gravity,  5.9  to  6.1 ;  composition,  CaO4W.  At  Glenorchy,  at  the 
head  of  Lake  Wakatipa,  I  examined  a  mine  which  had  been  worked  for  this 
mineral. 

f  In  this  particular  case,  those  working  the  mine  had  little  comprehension  of  the 
formation.  I  was  informed  that  there  were  several  "  false  hanging-walls,"  but  that 
there  was  only  one  foot-wall,  which  was  said  to  be  of  a  different  rock,  much  harder 
than  the  hanging.  On  examination,  I  found  the  rock  of  the  so-called  foot-wall  to 
be  similar  to  that  of  the  rest  of  the  country  enclosed  by  the  lode ;  and  on  crushing 


THE   GOLD-FIELDS    OF   OTAGO. 

The  chief  lode-raining  or  "reefing"  district  of  Otago,  which  lies 
north  of  Lake  Wakatipu,  presents  a  great  contrast  to  that  which 
surrounds  Waipori.  The  latter  consists  of  peculiarity  monotonous 
rounded  hills,  covered  with  a  peaty  soil  on  which  the  tussock  grass 
of  the  ridges  and  the  flax  .in  the  gullies  are  the  only  vegetation- 
The  rounded  outlines  of  these  foot-hills  have  been  ascribed  to  glacial 
erosion  in  the  same  way  that  much  else  in  Otago  is  put  down  to  this 
little  understood  agency.  However  that  may  be,  we  have  here  the 
basal  wrecks,  the  stumps,  as  it  were,  of  what  were  once  mountains, 
perhaps  as  rugged  as  those  further  inland.  Denudation  has  de- 
graded them  to  uninteresting  hillocks,  and  the  peaty  soil  which  covers 
them  now  serves  to  protect  them  from  rapid  erosion.  Farther  inland, 
the  foot-hills  become  more  striking  to  the  eye  by  reason  of  the  very 
curious  weathering  which  has  left  numerous  isolated  rocks  standing 
above  the  surrounding  level  like  an  army  in  skirmishing  order.  See 
Fig.  3. 

These  have  been  sometimes  supposed  to  be  the  rocky  freight 
brought  down  by  glaciers ;  but  they  are  in  situ,  and  the  explanation 
of  their  occurrence  is  difficult.  The  peculiar  weathering  which 
originated  the  names  Rock  and  Pillar.  Raggedy  Ridge,  Rough  Ridge, 
etc.,  given  to  some  of  the  hills  of  Otago,  is  not  of  uniform  occur- 
rence, being  less  marked  as  the  coast  is  approached.  I  have  noticed 
that  the  schist  of  which  these  isolated  rocks  are  composed  is  usually 
more  siliceous  than  that  of  the  surrounding  country,  and  I  would 
suggest  that  it  is  the  irregular  segregation  of  siliceous  material  which 
has  induced  this  very  unequal  weathering. 

At  Barewood,  where  I  examined  a  large  number,  I  found  that, 
almost  without  exception,  each  of  these  pillars,  usually  about  10  or 
15  feet  high,  contains  a  cup-shaped  hollow  of  varying  size.  This 
is  on  the  side  towards  which  dip  the  prevailing  quartzose  schists 
of  which  they  are  composed  ;  and  it  is  doubtless  due  to  the  forma- 
tion first  of  a  small  hollow  by  the  action  of  rain-water,  followed  by 
the  removal,  by  wind  and  rain,  of  some  of  the  softened  mica-schist. 
In  the  concavity  so  formed,  rain-water  would  lie,  and,  by  the  aid  of 
frost,  would  shatter  the  interfoliated  quartz.  Along  the  banks  of 
the  mountain  torrents  this  action  has  progressed  more  rapidly,  and 
the. rocks  exhibit  a  honey-combed  appearance. 


it  and  testing  it  with  the  "dish  "  or  pan,  it  was  found  to  be  richer  than  the  portion 
then  being  mined.  It  was  scarcely  necessary  after  that  to  advise  the  miners  to  put 
a  cross-cut  into  the  "  foot-wall." 


10  THE   GOLD-FIELDS   OF   OTAGO. 

To  return  to  the  northern  mining  districts.  The  region  about 
Lake  Wakatipu,  in  which  they  occur,  is  crossed  by  the  snowy  ranges 
of  the  Southern  Alps,  10,000  to  12,000  feet  in  height,  the  highest 
summit,  Mt.  Cook,  having  the  altitude  of  12,350  feet.  By  the 
sculpture  of  frost  and  snow,  the  structure  of  the  mountains  has  been 
laid  bare ;  and  though  they  are  carved  from  the  same  rocky  mate- 
rial as  the  lower  country,*  the  rugged,  bleak,  precipitous  ranges,  with 
their  coronets  of  snow,  are  in  strong  contrast  to  the  rounded  contours 
of  the  brown-paper-like  hillocks  around  Waipori. 

In  this  district,  Arrowtown,  Macetown,  and  Skippers  are  three  of 
the  best-known  mining  centers.  At  Macetown,  near  the  head  of 
the  Arrowf  river,  are  the  Tipperary,  Premier,  and  Sunrise  mines. 

The  Premier,  at  the  foot  of  Advance  Peak,  offers  several  points  of 
interest.  A  series  of  three  nearly  parallel  lodes  is  met  by  a  counter- 
lode,  and  at  the  junctions  ore-shoots  occur.  The  two  cross-sections, 
Figs.  4  and  5,  indicate  the  relative  positions  of  the  members  of  this 
lode-system.  The  dip  of  the  No.  2  or  main  lode  brings  it  across 
the  others,  which  are  thereby  deflected,  but  not  cut.  At  the  meet- 
ing-point ore-bodies  occur ;  but  so  far  only  one  of  these  junctions — 
the  lower  junction  of  the  No.  2  and  the  No.  3 — has  been  thoroughly 
developed.  The  ore-shoot  there  found  has  a  flat  inclination  (about 
45°)  along  which  it  was  followed  by  a  series  of  irregular  workings. 
There  is  always  a  clear  division-plane,  or  "  wall/'  between  the  two 
lodes  when  after  the  junction  they  are  seen  to  go  forward  in  com- 
pany. 

The  cross-cut  from  the  lower  adit  to  the  No.  2  lode  indicates  the 
relation  of  the  lodes  to  the  quartzose  schist  of  the  country.  See  Fig. 
9.  The  folia  of  quartz  (dipping  about  20°)  which  are  flat  in  the 
country  become  more  nearly  vertical  as  the  lode  B  is  approached. 
They  become  broken  by  fractures  A  A,  which  can  be  followed  until 
they  lose  themselves  in  the  vertical  lamination  of  the  schist  encas- 
ing the  quartz  of  the  "  reef."  Fig.  10  shows  the  appearance  of  the 
No.  1  reef  as  seen  in  the  back  of  the  level,  the  sketch  being  in  plan 
or  horizontal  section.  The  width  of  the  lode  proper  is  15  to  18 
inches,  strike  N.W.,  dip,  75°  to  80°.  On  the  foot-wall  side  there 
are  a  couple  of  inches  of  "  pug  "  or  selvage,  on  the  opposite  wall 

*  Quartzose  schist.  This  refers  only  to  the  mountains  in  the  vicinity  of  the 
raining  districts  cited.  The  main  ranges  westward  are  formed  in  part  of  granitic 
rocks. 

f  So-called  because  not  straight — lucus  a  non  lucendo.  In  riding  from  Arrowtown 
to  Macetown  the  track  crosses  the  winding  river  twenty-five  times  in  10  miles. 


- 


z 

s 

cc. 

UJ 

i 

LJ 

cr 

Q- 


A/fV^jMVV'.V 

\rJl)V\i-M\ 

Li»    *      .    ^S^^      / 


12  THE   GOLD-FIELDS    OF    OTAGO. 

there  is  none,  the  lode  passing  gently  into  the  country-rock.  The 
foliated  quartzose  schist  included  between  the  limits  of  the  lode  is 
very  beautifully  contorted.  The  schist,  both  that  included  within 
the  lode  and  that  encasing  it,  is  very  quartzose,  the  seams  being 
about  J  to  J  inch  thick.  The  lode  as  such  contains  irregular  pieces 
of  quartz ;  but,  as  a  whole,  it  carries  very  little  more  quartz  than  the 
enclosing  schist. 

Fig.  11  is  a  sketch  of  the  No.  2  lode,  taken  in  the  stopes  75  feet 
above  the  main  adit.  The  "  reef"  consists  of  B  B,  sugary  quartz 
about  4  to  5  inches  wide.  Fig.  1 2  is  also  close  by.  R  R  is  crushed 
quartz;  D  is  broken-up  material  in  which  quartz  predominates;  C 
is  foliated  quartzose  schist.  The  so-called  "foot- wall,"  A  A,  con- 
sists of  a  division-plane  marked  by  black  clay.  There  are  also 
similar  partings  between  R  and  D,  and  C  and  D.  Quartz  is  found 
behind  both  the  so-called  walls.  B  B,  the  auriferous  portion  of  the 
lode,  steps  from  one  side  to  the  other,  advancing  southeast.  The 
so-called  walls,  while  they  last,  are  clean  and  marked  by  a  graphitic 
surface,  accompanied  with  clay;  but  they  continue  their  course 
through  the  country-rock  after  the  quartz  has  left  tnem,  to  be  formed 
again  along  other  nearly  parallel  similar  divisions. 

At  the  Sunrise  mine,  on  Advance  Peak  (Fig.  13),  a  similar  type 
of  lode  occurs.  The  lode  is  divided  by  a  number  of  distinct  part- 
ings accompanied  with  unctuous  clay.  Tne  country-rock  near  the 
lode  is  conformable  to  the  "walls"  of  the  lode.  C  is  the  "  reef," 
consisting  of  crushed  mottled  quartz,  carrying  pyrites  and  stibnite ; 
A  is  clayey,  soft  and  broken ;  B  is  very  much  contorted  quartzose 
schist ;  D  is  of  similar  material ;  E  is  more  regular,  and  F  is  the 
country-rock  itself.  The  total  width  is  4  feet  8  inches.  It  is  ex- 
pected that  BCD  will  form  the  width  of  the  lode  as  the  level  is 
advanced. 

These  two  mines  illustrate  a  type  of  lode,  the  structure  of  which 
is  rendered  evident  by  the  peculiar  rock  in  which  it  occurs.  I  leave 
the  further  consideration  of  this  interesting  formation  until  I  shall 
have  passed  in  review  the  lodes  at  Skippers. 

Macetown  is  divided  from  Skippers  by  a  high  ridge  (6000  feet) 
overlooking  the  Shotover  river,  which  flows  between.  Ascending 
this  ridge  at  Advance  Peak,  one  obtains  a  fine  view  of  the  configur- 
ation of  the  country.  The  natural  beauty  of  mountain  land  is  de- 
stroyed by  the  severe  weathering,  which  has  prevented  the  growth 
of  timber,  save  in  sheltered  corners.  The  ranges  extend  in  their 
nakedness  like  the  skeleton  of  some  huge  saurian.  Their  structure 


THE   GOLD-FIELDS   OP   OTAGO.  13 

can  be  readily  discovered ;  the  dip-slopes  are  debris-strew  and  in- 
cline at  a  low  angle,  while  the  opposite  faces  are  precipitous  and 
rocky  in  the  extreme,  cut  up  by  well-marked  systems  of  jointage. 
On  the  summits  of  the  ridges  the  soft  schists  show  the  evidence  of 
the  easy  and  rapid  degradation  which  they  undergo  when  exposed  to 
the  snow  and  frost  of  these  higher  altitudes.  Landslips  on  a  large 
scale  are  common  and  temporarily  dam  or  permanently  divert  the 
mountain  streams,  causing  heavy  floods,  such  as  the  historic  one  of 
1878,  which  altogether  changed  the  distribution  of  the  auriferous 
beaches  of  the  Shotover  river. 

The  reefs  at  Skippers  are  perhaps  the  best  known  of  the  Otago 
lodes,  on  account  of  the  Phoenix  mine,  locally  celebrated  as  the  first 
to  utilize  the  electric  transmission  of  power  for  the  working  of  its 
stamp-mill.  Like  the  other  lodes  we  have  considered,  those  of 
Skippers  consist  of  a  system  of  several  gold-bearing  quartz-veins 
traversing  a  more  or  less  defined  ore-channel.  The  lodes  are  three 
in  number,  forming  a  lode-channel  which  dips  north  and  has  a 
variable  strike  of  about  N.  80°  W.  They  are  known  as  the  North, 
Middle  and  South  lodes  respectfully,  and  frhe  Middle  is  the  richest 
and  strongest  vein,  and  the  main  ore-producer.  They  are  approxi- 
mately parallel ;  but,  even  when  close  together,  never  lose  their  in- 
dividuality. There  is  a  good  hanging- wall  to  the  north  of  the  series 
and  a  good  foot  to  the  south  ;  but  the  intermediate  walls  of  the  dif- 
ferent members  of  the  series  are  irregular  and  indistinct.  The 
shoots  of  gold-bearing  stone  have  two  marked  features.  The  first 
is,  that  they  make  in  step-like  gradation  from  one  lode  to  the  other. 
Shoots  on  any  two  lodes  are  never  opposite  each  other,  whether  in 
vertical  or  horizontal  section.  It  is  almost  the  converse  of  "ore 
against  ore."  See  Figs.  6  and  7.  The  other  noteworthy  character- 
istic of  this  system  of  gold-veins  is  that  they  are  particularly  poor 
when  their  strike  is  south  of  west,  while  they  are  almost  invariably 
found  to  become  gold-bearing  whenever  a  turn  takes  place  to  the 
north  of  west.  As  the  result  of  these  two  features,  it  is  found  in  the 
working  of  the-  mine  that  one  lode  is  rarely  rich  for  any  great  dis- 
tance ;  that  when  it  is  gold-bearing  in  a  given  portion,  the  portions 
of  the  other  two  lodes  which  are  immediately  opposite  will  be  poor; 
that  when  it  becomes  barren  the  gold  is  to  be  looked  for  at  a  point 
opposite  in  one  of  the  two  other  lodes;  and  of  the  two,  in  that  one 
whose  course  at  that  point  is  north  of  west. 

The  mine  is  worked  by  adits.  At  the  level  of  the  No.  3  adit  the 
south  lode  is  intersected  at  96  feet  from  day-light,  the  Middle  at  24 
feet  beyond,  and  the  North  at  60  feet  further  still. 


THE   GOLD-FIELDS   OF   OTAGO.        .  15 

The  shoots  of  gold-bearing  stone  are  from  50  to  200  feet  in  length ; 
for»the  most  part  they  pitch  strongly  to  the  west,  but  are  not  con- 
tinuous in-  depth.  However,  as  one  ore-shoot  comes  to  an  end, 
another  is  discovered  below ;  and  the  deeper  workings  expose  ore- 
bodies  which  do  not  extend  to  the  surface.  A  cross-course  cuts  the 
lodes  at  a  strong  angle,  faulting  the  Middle  lode,  which  on  the  east 
side  was  called  the  "  Promised  Land  "  lode  until  it  was  recognized 
as  a  faulted  portion  of  the  Middle  lode.  Immediately  east  of  the 
cross-course  the  lode  was  very  rich.  Fig.  14  illustrates  the  Main 
lode  as  seen  in  the  150-foot  level  stopes.  A  is  disordered  soft 
country  lying  against  the  hanging.  B  is  f<  payable  stone  " — quartz 
and  included  country  merging  into  each  other ;  the  quartz  is  dark 
and  mottled,  carrying  a  small  percentage  of  arsenical  pyrites.  The 
gold  is  coarse  and  often  visible.  C  is  country-rock  included  within 
the  lode  and  arranged  parallel  tp  the  foot- wall  which  it  follows. 
The  whole  width  is  8  feet.  A  is  2|  feet.  C  is  3  feet. 

The  reefs  of  Skippers,  Macetown  and  Waipori  have  certain  fea- 
tures in  common,  due  to  the  identity  of  the  country-rock  which  they 
traverse,  and  probably  also  to  their  contemporaneous  origin.  In 
each  case  the  structure  is  that  of  a  group  of  lodes  rather  than  of  one 
single  vein.  The  series  of  two  or  more  approximately  parallel  reefs 
occupying  fractures  formed  along  a  more  or  less  defined  belt  repre- 
sents the  relief  given  to  the  compression  of  the  rocks  by  a  large 
fault-fissure  such  as  that  of  the  Comstock  vein.  The  contortion  ob- 
servable in  the  country  included  within  the  limits  of  the  ore-chan- 
nel, and  the  frequent  partings  which  are  also  lines  of  faulting,  lead 
one  to  the  belief  that  more  than  one  movement  of  varying  intensity 
took  place.  The  fine-grained,  closely  foliated  quartzose  schists 
yielded  in  part,  by  the  formation  of  folds,  to  the  compression  to 
which  they  were  subjected,  while  the  strain  was  further  taken  up  by 
the  production  of  a  set  of  co-ordinated  fissures.  Along  these  lines, 
later  movements  crushed  the  intervening  enclosed  country,  and  thus 
by  preparing  a  channel  for  the  percolation  of  mineral  solutions,  cre- 
ated in  a  varying  degree  the  locus  of  gold-deposit. 

The  outside  members  of  any  such  system  of  lodes  usually  have 
walls  which  respectively  form  the  boundaries  of  the  ore-channel. 
Such  walls  are  usually  accompanied  by  a  varying  thickness  of  black 
clay  or  gouge.  Generally  speaking,  however,  the  distinction  be- 
tween "country"  and  "reef"  is  arbitrary.  The  quartz  of  the  reef, 
the  quartzose  schist  of  the  included  country,  and  the  somewhat  less 
quartzose  schist  of  the  enclosing  country  shade  off  imperceptibly. 


16  .         THE   GOLD-FIELDS   OF   OTAGO. 

Sometimes  there  is  no  line  of  division  between  the  reef  and  the  en- 
closing rock;  at  other  times  there  is  a  line  of  parting,  which  is  Sig- 
nified by  the  name  of  "foot-wall  "  or  "  hanging-wall." 

There  is  reason  to  believe  that  the  quartz  of  the  lodes  sometimes 
occupies  fractures  formed  along  the  axes  of  anticlinal  folds  ;  but,  as 
a  rule,  tbe  type  of  structure  is  that  shown  in  miniature  in  Fig.  8 
from  a  sketch  made  by  me  from  a  cutting  on  the  Shotover  main 
road.  The  sketch  covers  a  width  of  5  feet.  Instead  of  forming  a 
narrow  clean-cut  crack  or  fissure,  the  soft  schist,  by  reason  of  its  in- 
terfoliated  quartz  which  renders  it  of  varying  hardness,  is  traversed 
by  a  belt  of  dislocated  country  bounded  by  two  parallell  fractures. 
The  interfoliated  quartz  enables  one  to  see  clearly  that  there  has 
been  a  movement  resulting  in  the  disarrangement  of  the  parallelism 
of  the  quartz  lamina?.  In  this  case  the  fracture  (from  a  to  6)  has  a 
width  of  only  7  inches;  but  the  structure  is  similar  in  origin  and 
kind  to  that  which  we  have  seen  forming  the  larger  lodes  of  the 
mines.  The  part  between  the  two  lines  of  fracture  forms  the  begin- 
nings of  the  "  mullocky  reef"  of  the  colonial  miner,  that  is,  a  lode 
carrying  a  large  proportion  of  included  country-rock.  Percolating 
waters  deposit  their  quartz  first  a'long  the  lines  of  parting,  and  we 
get  a  twin  system  of  veins;  and  if  the  action  be  continued  further, 
the  intervening  filling  is  also  silicified.  It  may  seem  a  long  step, 
from  a  lode  like  the  Premier,  the  larger  part  of  which  is  gold-bear- 
ing material  which  is  crushed,  included  country-rock,  to  a  massive 
vein  of  clean  auriferous  quartz ;  yet  in  truth  the  difference  is  not  of 
origin  of  structure,  but  of  degree  only,  being  due  to  the  variable 
extent  to  which  quartz  has  replaced  the  country-rock. 

Before  leaving  this  part  of  the  subject,  I  would  venture  the  sug- 
gestion that  lode-mining  in  Otago  has  a  future  scarcely  to  be  inferred 
from  the  scanty  results  hitherto  obtained.  Examination  of  the  lodes 
shows  that  they  are  found  in  channels  but  little  divided  from  the 
main  mass  of  the  country- rock,  and  that  the  quartzose  schists  are 
auriferous  in  themselves,  outside  the  boundaries  of  such  lode-chan- 
nels. The  formation  strongly  points  to  the  probability  that  there 
will  be  found  certain  belts  of  country-rock  sufficiently  auriferous  to 
become  mines.  At  present,  gold-milling  in  Otago  is  in  a  very  crude 
condition ;  but  with  the  improvements  made  in  the  treatment  of 
gold-quartz  ores  and  the  consequent  decrease  of  the  cost  of  handling 
them,  there  will  come  a  day  when  large  "low-grade  gold-proposi- 
tions" will  give  lode-mining  in  this  part  of  New  Zealand  an  im- 
portance now  unsuspected. 


THE   GOLD-FJELDS   OF   OTAGO. 


17 


— 

d> 


18  THE  GOLD-FIELDS  OF  OTAGO. 

ALLUVIUM. 

The  alluvial  deposits  of  Otago  are  far  more  developed  than  its 
quartz  lodes.  The  extent  of  the  gold-bearing  alluvium  lying  among 
the  highlands  of  the  province  is  imperfectly  known ;  but  so  far  as 
it  has  been  explored,  all  facts  point  to  the  conclusion  that  it  is  enor- 
mous. The  gravel-deposits  present  many  features  in  marked  dis- 
tinction to  those  of  California  and  Australia,  between  which  two 
there  is,  on  the  contrary,  a  striking  resemblance.*  The  gold-drifts 
of  California  are  chiefly  in  the  Pliocene,  and  so  are  those  of  Victoria ; 
but  the  alluvial  gravel  of  Otago  belongs  to  the  Lower  Miocene  and 
to  other  periods.  The  beds  of  lava  which,  in  both  California  and 
Victoria,  are  found  capping  the  alluvium  are  conspicuously  absent 
in  Otago,  where,  moreover,  the  deeper  lying  drifts  are  not  so  impor- 
tant a  source  of  gold  as  the  more  shallow  deposits  of  the  rivers. 

The  gold  is  usually  in  fine  flakes,  and  only  the  uppermost  reaches 
of  the  rivers  show  the  nuggetty  character  of  other  districts.  Nug- 
gets of  any  size  are  very  rare,  and  the  largest  on  record  weighed,  as 
already  observed,  only  27  ounces,  while  California  can  boast  of  one 
found  in  Calaveras  county,  f  weighing  195  pounds,  and  worth  $43,- 
534,  and  Victoria  has  furnished  the0  Welcome  Stranger/'  weighing 
£248  ounces,  and  wortfi  £9534  or  $47,670.  f 

The  great  extent  of  the  Otago  alluvium  is  due  to  a  combination 
of  causes,  among  which  the  character  of  the  prevailing  rock  and  the 
low  snow-line  are  the  most  important.  The  limit  of  perpetual  snow 
is  at  about  7000  feet  above  the  sea.  The  prevailing  rock  is  the 
quartzose  schist,  which  is  very  rapidly  eroded,  and  the  debris  from 


*  Yet,  notwithstanding  this  well-known  fact,  it  is  curious  to  note  how  very  little 
Victorian  and  Californian  geologists  and  engineers  seem  to  know  or  care  to  know 
of  each  other's  work.  Investigations  are  twice  made,  and  ground  is  twice  covered, 
owing  to  this  want  of  intercommunication. 

f  According  to  a  statement  made  by  John  Hays  Hammond  in  the  Ninth  Annual 
Report  of  the  State  Mineralogist  of  California.  Dr.  Raymond  gives,  in  the  Report 
of  the  U.  S.  Commission  of  Mines  and  Mining  for  1869  (published  1870),  p.  452,  a 
list  of  famous  Australian  and  Californian  nuggets,  including  two  from  California, 
weighing  106  and  160  pounds  respectively,  and  half  a  dozen  from  Australia,  rang- 
ing from  112  pounds  upwards,  the  heaviest  two  being  the  Ballarat  nugget  of  1853, 
weighing  168  pounds,  and  the  famous  "  Sarah  Sands,"  weighing  223  pounds,  4 
ounces. 

J  The  "  Welcome  Stranger"  was  found  at  Moliagul,  near  Dunolly,  February  5, 
1869.  Though  several  bits  had  been  previously  broken  off  by  the  discoverers,  it 
yielded,  on  melting,  2268  ounces,  10  pennyweights,  14  grains.  The  original 
nugget  contained  2280  ounces  of  melted,  or  2248  ounces  of  pure  gold,  being  valued 
at  the  Bank  of  England  at  £9534. 


THE   GOLD-FIELDS   OF   OTAGO.  19 

which  is  washed  down  into  the  great  natural  tail-races  of  the  Clutha, 
Shotover  and  Kawarau  rivers.  These  rivers  are  subjected,  by  the 
rapid  thawing  of  large  masses  of  snow,  to  frequent  flooding  and  the 
diversion  of  their  channels  by  the  detritus  brought  down.  The  soft 
character  of  the  bed-rock  soon  makes  a  temporary  channel  a  perma- 
nent one ;  and  so  it  happens  that,  even  at  the  higher  altitudes,  ter- 
races of  gravel  and  old  river-beds  are  frequent  and  form  prolific 
sources  of  the  precious  metal. 

The  most  extensive  alluvial  deposits  are  found  along  the  course 
of  the  Clutha,  formerly  called  the  Molyneux.  This  river  is  to  the 
miners  of  Otago,  in  some  respects,  what  the  Nile*  is  to  the  Egyptian 
fellaheen,  though  it  is  the  great  artery,  not  of  fertile^  lowlands,  but 
of  auriferous  highlands.  The  anxious  cultivator  beside  the  banks  of 
the  historic  northern  river  does  not  watch  the  rise  and  fall  of  its 
waters  with  more  anxiety  than  does  the  energetic  New  Zealander  the 
rapid  current  of  the  southern  stream,  whose  quick  rise  or  gradual 
fall  may  mean  on  the  one  hand  the  cessation  of  work  and  the  flood- 
ing of  claims,  or,  on  the  other,  the  steady  ingathering  of  a  golden 
harvest. 

The  Clutha  affords  some  interesting  lessons  in  physical  geography- 
With  its  seven-knot  current,  it  sweeps  down  through  'the  easily 
eroded  schistose  rocks  in  which  it  has  cut  for  itself  a  natural  sluice- 
box,  the  riffles  of  which  are  the  rocky  bars,  while  its  head  is  at  the 
feet  of  the  glaciers,  and  its  lower  end  empties  into  the  Pacific. 
Where  the  river  now  flows  there  was  once  a  chain  of  fresh- water 
lakes,  cut  out  by  the  glaciers  which  have  now  retired  further  inland. 
These  lakes  received  the  tribute  of  the  upper  highlands  in  the  form 
of  the  gold-bearing  gravel  which  was  deposited  on  their  bottom.  In 
later  times  the  Clutha  worked  it  way  from  lake  to  lake,  and  finally, 
having  worn  down  its  channel  deeply  through  the  schists,  it  emptied 
the  lakes,  cut  through  the  deposits  which  had  been  formed  in  them, 
and  now  flows  unfettered  to  the  sea. 

The  main  features  of  the  country  through  which  it  passes  are  bare 
mountain  ridges  of  high  elevation,  diversified  by  narrow  valleys  of 
pastoral  land.  Narrow  rocky  gorges  separate  wide  flats  of  evidently 
lacustrine  origin.  That  part  of  the  river  from  the  Island  Block  to 
Alexandra  is  typical.  At  the  former  point  there  occurs  an  old  chan- 
nel, separated  from  the  new  by  a  ledge  of  rocks ;  and  above  the 

*  It  has  been  stated  that  the  Clutha  carried  a  volume  of  water  equal  to  that  of 
the  Nile.  The  estimation  of  the  Clutha  was  correct,  but  the  Nile  was  probably  in- 
correctly gauged. 


oz 

£  t 

CO     CO 


-I     Q 
CO 


THE   GOLD-FIELDS   OF   OTAGO.  21 

junction  of  the  two  channels  there  is  a  narrow  gorge,  which  is  suc- 
ceeded by  the  wide  flats  of  Ettrick,  through  the  eastern  side  of  which 
the  river  has  cut  its  way.  Then  follows  another  rocky  canon,  to  be 
succeeded  by  the  small  lake-basin  in  which  the  Hercules  Company 
is  finding  "  pay  gravel."  Continuing  north,  below  Roxburgh  bridge, 
comes  a  short  rocky  cutting  which  opens  out  into  Coal  Creek  flat, 
from  which  it  is  6  miles  to  Coal  Creek  gorge,  and  then  25  miles  of 
narrow  ravines  to  the  Alexandra  terraces  which  mark  the  successive 
levels  of  an  old  lake. 

Tne  Island  Block  is  now  the  scene  of  important  mining  operations. 
There  the  present  river  (see  Fig.  15)  flows  on  the  eastern  side  of  a 
rocky  ridge  which  forms  an  island  between  the  river  of  to-day  and 
that  of  a  former  period.  The  old  river-channel,  about  J  mile  wide 
and  4J  miles  long,  is  marked  by  a  valley  of  the  most  valuable  pas- 
toral land  in  Otago.  Its  upper  end  opens  out  towards  the  banks  of 
the  present  river,  but  forms  a  narrow  gorge  at  its  lower  end  where 
(at  the  point  marked  by  a  cross  in  Fig.  15)  the  Island  Block  Com- 
pany is  working.  The  configuration  of  the  valley  is  further  shown 
in  Fig.  16,  in  which  sketch  C  is  the  island,  A  the  point  where  the  old 
and  new  channels  meet,  which  is  overlooked  in  the  distance  by  B,  the 
Old  Man  Range,  D  indicates  the  lower  slopes  of  the  Spylaw  Hills. 

The  Island  Block  Company  commenced  work  at  the  immediate  out- 
let of  the  old  channel ;  but  it  was  found  that  there  was  here  a  narrow 
deep  rocky  gorge,  the  overhanging  sides  and  rapidly  shelving  bottom 
of  which  had  prevented  the  deposition  of  the  gold.  Going  inland, 
the  channel  widened,  and  the  bottom  became  less  steep.  Soon 
however  the  gravel  was  cut  off  by  a  bar  of  rock.  It  was  then 
decided  to  test  the  channel  at  a  point  nearer  the  center  of  the  valley ; 
but  on  bottoming,  hard  schist  was  encountered  at  60  feet,  and  no  pay 
gravel  was  found.  The  next  step  was  to  cut  right  across  the  sup- 
posed line  of  channel.  This  met  with  success.  On  the  south  side, 
after  having  raised  50,000  cubic  feet  of  barren  material  the  elevator 
bottomed  upon  "  a  lead  "  3  to  4  feet  thick,  and  carrying  rich  gravel. 
Mining  operations  have  thus  shown  that  the  old  channel  is  more 
irregular  than  would  at  first  sight  be  supposed.  Fig.  19  exhibits 
the  arrangement  of  the  large  boulders  which  lie  upon  the  bed  rock. 
The  gold  is  found,  in  the  heavy  silt  which  has  been  caught  among 
the  interstices  of  the  boulders,  the  arrangement  of  which  forms  a 
natural  riffle,  resembling  the  "  pavement-riffle7'  of  the  miner. 

At  Waipori  there  is  a  similar  deposit  in  the  old  bed  of  the  Lam- 
merlaw  Creek.  It  is  shown  in  plan  and  section  in  Figs.  17  and  18. 


22  THE   GOLD-FIELDS    OF   OTA  GO. 

The  deposit  has  a  depth  of  54  feet  and  a  width  varying  from  25  to 
30  feet.  The  sides  are  very  irregular,  and  there  are  several  distinct 
layers  of  gravel,  making  "  false  bottoms."  The  origin  of  this  old 
channel  is  easily  explained.  The  country  rock  is  here  traversed  by  a 
lode,  the  croppings  of  which  have  been  found  in  the  bed-rock.  They 
contain  gold,  and  have  a  strike  which  brings  them  in  line  with  the 
"  Ofcago  Pioneer  Quartz"  lode  worked  on  the  opposite  hill.  (This 
is  somewhat  after  the  manner  of  the  deep  leads  of  Ballarat,  where, 
when  the  alluvial  deposits  had  been  worked  out,  the  mines  had  a 
second  lease  of  life  through  the  development  of  the  quartz-veins,  the 
croppings  of  which  had  been  found  in  the  bed-rock  of  the  alluvium.) 
Here  the  lode-channel,  consisting  of  rock  softer  than  the  average, 
offered  an  easy  passage  for  the  Lammerlaw,  on  its  way  to  join  the 
Waipori  river.  Having  become  filled  up  during  a  time  of  flood, 
the  channel  was  diverted  and  formed  the  Lammerlaw  Creek  of 
to-day. 

Near  Waipori  is  the  celebrated  Blue  Spur.  This  is  perhaps  the 
best  known  and  most  interesting  alluvial  deposit  in  New  Zealand. 
It  is  situated  near  the  head  of  Gabriel's  Gully,  about  two  miles  east 
of  the  town  of  Lawrence.  The  name  is  derived  from  the  color  of 
the  alluvium  which  was  first  discovered  in  the  gully  at  the  foot  of 
the  spur  into  which  it  was  afterwards  traced.  The  blue,  or,  more 
accurately  greenish-blue,  tint  is  probably  due  to  the  silicate  of  the 
protoxide  of  iron.  The  deposit  consists  of  a  mass  of  cement  and 
conglomerate,  occupying  a  cup-shaped  hollow  in  a  ridge  or  spur 
which  divides  two  nearly  parallel  gullies.  Figs.  20,  21  and  22  illus- 
trate it.  Fig.  20  is  a  cross-section.  The  con  tour-line  of  the  ridge  as 
here  shown  is  obtained  from  an  old  photograph  taken  in  1865.  The 
working  of  the  deposit  has  entirely  altered  the  lines.  The  longer 
axis  is  nearly  at  right  angles  to  the  present  trend  of  the  Blue  Spur 
ridge,  the  depression  which  the  deposit  fills  having  been  cut  out  of 
the  Wanaka  schistsr  the  characteristic  rocks  of  Otago.  Fig.  22  gives 
the  longitudinal  section.  The  gully  on  either  side  is  partially  filled 
with  tailings. 

The  plan,  Fig.  21,, shows  the  deposit  to  have  a  roughly  oval  shape, 
the  longer  axis  having  a  strike  N.  60°  W.,  and  a  length  of  about 
S^chains,  the  shorter  or  N.E.-S-.W.  axis  is  22  chains  in  length. 

For  the  sake  of  brevity,  the  two  longer  sides  of  the  deposit,  facing 
respectively  N.E.  and  S.W.,  will  be  spoken  of  as  the  "  Lawrence  " 
and  the  "  further  side."  On  ascending  the  ridge  on  the  further  side, 
about  400  feet  above  the  present  level  of  Gabriel's  Gully,  the  country 


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24  THE   GOLD-FIELDS   OF   OTAGO. 

presents  the  appearance  roughly  indicated  in  Fig.  21 .  The  accumula- 
tion of  tailings  will  in  part  explain  the  increased  width  of  the  gullies 
at  a  point  opposite  the  deposit;  but  there  is  no  doubt  that  this  is 
also  due  in  a  large  measure  to  the  erosion  of  the  conglomerate  which 
formerly  extended  across.  In  both  instances,  the  gullies  narrow 
rapidly  above  their  intersection  with  the  larger  axis  of  the  deposit, 
and  at  a  short  distance  become  merely  rocky  ravines.  It  is  also 
noteworthy  that  there  are  marked  lateral  gullies  which  correspond 
to  the  line  of  the  deposit. 

The  gold  first  discovered  in  Otago,  the  discovery  of  which  inaugu- 
rated the  rush  to  the  New  Zealand  gold-fields,  was  derived  from  this 
mass  of  wash.  Neither  Gabriel's  nor  Munro's  gully  proved  rich 
above  their  intersection  with  the  deposit,  while  both  were  particu- 
larly rich  at  and  immediately  below  that  intersection. 

The  mass  of  the  cemented  conglomerate  has  been  variously  esti- 
mated at  from  8  to  10  million  cubic  yards,  but  the  present  manager ;* 
whose  opinion  is  of  the  most  value,  puts  it  at  from  11  to  12  millions. 
The  area  covered  is  45  acres. 

A  nearer  view  of  the  deposit  presents  the  following  features.  On 
the  Lawrence  side,  the  rock  forming  the  rim  of  the  cup-shaped 
hollow  presents  a  very  uneven  surface,  and  the  folia  of  the  schist 
are  much  distorted  and  fractured.  The  pebbles  of  the  conglomerate 
are  imbeded  in  the  soft  crushed  country,  there  being  no  distinct 
boundary  or  line  of  demarcation  between  the  deposit  and  the  sur- 
rounding country-rock.  There  are  longitudinal  furrows  in  the  schist, 
parallel  to  the  strike  of  the  country  and  the  longer  axis  of  the  deposit. 
These  furrows  are  not  regular  either  in  shape  or  direction.  Looking 
down  from  the  ridge  on  this  side,  the  enormous  masses  of  wash 
present,  by  reason  of  their  unequal  erosion,  the  appearance  of  a 
miniature  cordillera.  Reddish  layers  of  oxidized  material  form 
marked  lines  through  the  general  faint  blue  tinge  of  the  cement,  and 
indicate  the  dip  of  the  deposit,  which  is  seen  to  be  at  a  low  angle 
toward  Gabriel's  Gully,  or  southeastward. 

Descending  among  the  masses  of  conglomerate,  one  can  observe 
the  structure  of  the  material.  Fractures  cut  through  the  included 
fragments  of  the  more  fissile  schist,  but  they  do  not  pass  through  the 
harder  pebbles.  These  last  are  of  varying  size  up  to  boulders  2  feet 
in  diameter.  The  wash  shows  a  large  proportion  of  schist-frag- 
ments, held  together  by  a  light  greenish-blue  fine-grained  cement. 

*  Mr.  Howard  Jackson,  to  whose  courtesy  the  writer  is  much  indebted. 


THE    GOLD-FIELDS    OF  OTAGO.  25 

Of  the  remaining  portions  of  the  material,  large  jasperoid  boulders 
are  most  prominent. 

Going  to  the  further  side  of  the  deposit,  it  is  seen  at  once  that  the 
rim-rock  has  an  altogether  different  appearance  from  that  noted  on 
the  Lawrence  side.  The  bounding  wall  is  perfectly  straight  and 
even,  with  a  dip  of  25°  30'  to  the  southwest.  It  shows  incrustations 
of  alum.  The  schist  of  the  country,  which  dips  with  the  face  of  the 
rim-rock,  shows  no  signs  of  having  been  crushed  or  dislocated.  When 
first  uncovered,  the  face  of  this  wall  is  said  to  have  been  (and  its 
present  appearance  suggests  it)  wonderfully  straight  and  smooth. 
Exposure  to  the  weather  has  induced  the  slow  shaling  off  of  its  sur- 
face, which  is  now  littered  with  the  thin  sherd-like  fragments  broken 
off  by  frost  and  rain.  Originally  the  rim-rock  was  covered  with  a 
thin  layer  of  clay  which  protected  it ;  but  this  clay  first  hardened 
and  then  cracked,  to  be  subsequently  removed  by  the  rain ;  and  the 
underlying  country-rock  is  being  rapidly  eroded.  Fig.  24  gives  a 
view  of  its  present  appearance.  C  D  is  the  face  of  the  rim-rock ; 
E  E  are  the  fragments  which  have  scaled  off  its  surface.  Along  A 
B  a  section  has  been  taken,  which  is  indicated  on  a  larger  scale  in 
Fig.  25.  In  this,  F  is  the  quartzose  schist  of  the  country ;  E  is  a 
chocolate  brown  indurated  clay  covering  the  rim-rock  itself;  D  con- 
sists of  a  J-inch  layer  of  hard  cement ;  C  is  a  2J  inch  layer  of  soft 
brown  mud ;  B  is  2J  feet  of  reddish  small  gravel ;  A  is  the  main 
body  of  cement  and  wash. 

Fig.  26  shows  the  arrangement  of  the  material  in  a  block  of  the 
conglomerate.  A  is  a  layer  of  large  pieces  of  the  quartzose  schist, 
but  sWghtly  rounded  ;  B  contains  smaller  brown  schistose  fragments; 
C  is  schist  rock,  containing  but  little  quartz;  D  is  a  band  of  bluish 
cement;  E  is  a  highly  quartzose  schist  bed;  F  contains  quartz  peb- 
bles, not  rounded ;  G  is  mixed  material,  quartz  fragments  and  schist 
irregularly  distributed  through  a  cement  matrix. 

Coming  toward  Gabriel's  Gully,  a  pink  layer  containing  lignite  is 
seen.  Near  the  gully,  mining  operations  have  partially  uncovered 
the  bed-rock  which  here  presents  the  features  shown  in  Fig.  27.* 
This  is  a  section  taken  along  a  line  N.  36°  W.,  making  an  angle 
of  14°  with  the  longer  axis  of  the  deposit.  At  the  present  time  the 
edge  of  the  rim-rock  is  laid  bare,  but  the  bed-rock  of  the  gutter 
itself  is  under  water.  It  is  seen  that  the  gutter  comes  abruptlv 

*  This  a  rough  copy  of  a  drawing  made  by  Mr.  Howard  Jackson,  who  was  good 
enough  to  allow  me  to  make  use  of  it. 


26  THE   GOLD-FIELDS   OF   OTAGO. 

against  a  ridge  over  60  feet  high  ;  from  the  foot  of  this  it  rises  gently 
towards  Munro's  Gully,  but  soon  meets  with  another  interruption  in 
the  form  of  a  wall  of  rock  over  20  feet  high,*  beyond  which  it 
slopes  away  again  before  taking  its  regular  rise.  Numerous  irregu- 
lar crevices,  found  in  the  bed-rock  of  the  gutter,  generally  contained 
a  great  deal  of  gold.  Above  this,  the  cement  was  very  variable  in 
its  gold-contents,  which  were  usually  arranged  along  certain  red 
bands.  Some  of  the  material  was  absolutely  non-auriferous ;  while 
other  portions  would  form  a  pudding-stone  of  golden  wash,  the  gold 
of  which,  as  distinguished  from  the  fine  flakey  character  which  it 
usually  had,  was  of  the  size  of  beans. 

While  the  rim-rock  rising  from  the  gutter  on  the  northeast  side 
was,  as  we  have  seen,  smooth  and  regular,  that  of  the  Lawrence  side 
was  rendered  remarkable  by  "  crab  •holes,"  as  they  were  called  by 
the  miners.  These  were  irregular  corrugations,  not  parallel  or 
straight,  but  narrowing  and  opening  out  at  intervals.  Fig.  23  is  a 
sketch;  roughly  representing  some  of  these  in  section.  These  cavi- 
ties were  as  much  as  15  feet  deep;  they  were  covered  with  a  casing 
of  cement  as  regular  as  plaster ;  and  the  material  which  filled  them 
was  a  different-looking  cement  from  that  of  the  main  body,  the  line 
of  division  between  the  two  being  so  marked  as  to  be  of  assistance  in 
blasting. 

The  northeast  wall  continues  underneath  the  Lawrence  rim-rock. 
In  working  along  the  smooth  face  of  the  northeast  rim,  a  party  of 
miners  followed  it  and  were  working  their  way  underneath  the  south- 
western "  reef"  f  before  they  discovered  their  mistake  by  hearing  the 
blasting  of  those  above  them. 

THE  GENESIS  OF  THE  BLUE  SPUR  DEPOSIT. 

The  above  concludes  the  general  description  of  a  deposit  the  origin 
of  which  is  a  subject  of  much  interest.  To  recapitulate  its  main 
features ;  it  consists  of  a  mass  of  cement  and  conglomerate,  lying  in 
a  depression  formed  in  the  quartzose  mica-schists  of  the  Wanaka 
series  and  transverse  to  the  present  water-shed  of  the  district.  The 
country  has  a  dip  of  15°  to  20°  southwest,  the  inclination  increasing 
near  this  deposit.  The  rock  on  the  N.E.  side  conforms  in  dip  to 

*  This  is  outside  the  limits  covered  by  the  section  given  in  Fig.  27  and  is  there- 
fore not  shown. 

f  The  Australian  and  New  Zealander  calls  the  rock  rising  from  the  bed-rock  of 
the  gutter  the  "reef."  It  must  not  be  confounded  with  the  same  word,  which  is 
used  as  a  synonym  of  lode,  ledge  or  vein. 


28  THE   GOLD-FIELDS   OF   OTAGO. 

the  bound! ng-wall  of  the  deposit  on  that  side.  On  the  Lawrence 
side,  there  is  no  conformity ;  the  schist  is  disordered  ;  and  the  boun- 
dary between  the  conglomerate  and  the  country-rock  is  almost  ob- 
literated. On  the  N.E.  side  the  bounding-wall,  when  first  uncov- 
ered, had  a  smooth,  polished  surface.  On  the  Lawrence  side  corru- 
gations and  irregular  holes  were  common  in  the  rim-rock.  The 
N.E.  wall  continues  underneath  the  face  of  the  opposite  side.  The 
gutter  itself  is  in  places  very  irregular ;  it  has  one  particular  break 
of  20  feet  in  height;  it  is  separated  from  Gabriel's  Gully  by  a  rocky 
ridge,  and  has  a  general  rise  towards  Mtinro's  Gully. 

The  deposit  has  a  roughly- bedded  struciure,  indicating  a  gentle 
dip  S.E.-ward  or  towards  Gabriel's  Gully.  The  wash  at  the  N.W. 
or  Munro's  Gully  end  is  the  coarsest.  Along  its  shorter  axis,  the 
dip  is  scarcely  noticeable,  save  near  the  edges.  It  is  more  flat  on  the 
Lawrence  side. 

Beds  of  lignite  occur,  confined  to  an  upper  horizon  of  the  deposit. 
The  dip  of  the  gutter  would  bring  the  conglomerate  above  the  pres- 
ent surface  as  we  go  northwest.  It  is  therefore  not  surprising  that 
no  traces  of  it  are  found  in  that  direction,  beyond  Munro's  Gully  ; 
for  erosion  has  removed  it.  Going  south-eastward,  however,  it  has 
been  uncovered  and  worked  in  the  next  parallel  gully,  Weather- 
stone's.  It  was  found  again  in  Waitahuna  Gully.  Along  the  same 
line,  other  smaller  patches  have  been  found  at  intervals,  and  finally 
at  Kaitangata,  according  to  Sir  James  Hector,  it  underlies  the  coal. 

The  Blue  Lead  in  Sierra  and  Nevada  counties,  California,  an  old 
river  of  Miocene  age,  was  to  the  Yuba  and  its  tributaries  what  the 
Blue  Spur  was  to  the  Tuapeka.  In  both  cases,  the  bulk  of  the  gold 
found  in  the  river-gravel  came  from  an  old  deposit,  the  course  of 
which  lay  at  right  angles  to  that  of  the  present  drainage-system. 

With  regard  to  the  age  of  the  Blue  Spur  deposit,  it  was  obviously 
formed  at  a  period  preceding  that  of  the  erosion  which  produced  the 
gullies  the  direction  of  which  it  crosses.  These  gullies  are  the 
source  of  streams  which  feed  the  Clutha,  whose  course  also  lies  across 
the  line  of  the  Blue  Spur  Lead.  The  Clutha  received  the  drainage 
of  glaciers  belonging  to  the  Pliocene  period.  The  Blue  Spur  is 
therefore  older  yet.  This  is  confirmed  by  its  occurrence  under  the 
coal-measures  of  the  Oamaru  formation  which  is  of  Eocene  or  Cre- 
taceo-Eocene  age.  It  is  thus  perhaps  the  oldest  gold  alluvium  which 
is  worked,  of  which  there  is  record. 

Its  origin  is  more  difficult  to  determine.  The  glaciers  were  in 
Eocene  times,  as  they  are  to-day,  the  great  natural  sculptors  of  the 


THE   GOLD-FIELDS   OF   OTAGO.  29 

face  of  Otago.  All  investigation  into  the  surface  geology  of  this 
portion  of  Xew  Zealand  points  to  this  agency  as  having  cut  out  the 
lake-basins  which  form  so  prominent  a  feature  of  the  country.  It  is 
glacial  action  which  is  generally  mentioned  as  explaining  the  origin 
of  the  Blue  Spur.  That  it  is  no  ordinary  ancient  river-deposit  is 
proved  by  the  contour  of  the  bed-rock ;  for  the  conglomerate  lies  in 
a  pot-hole  rather  than  in  a  regular  channel.  While  the  general 
slope  is  gently  southeastward,  the  lower  end  at  Gabriel's  Gully  is 
found  to  be  bounded  by  a  rocky  ridge  fully  75  feet  in  height;  and 
midway  between  the  two  gullies  another  rapid  rise  of  20  feet  is  en- 
countered. Such  a  configuration  is  best  explained  by  considering  it 
as  a  pot-hole  or  hollow  scooped  out  by  ice-action.  Though  there 
are  no  stria?  or  markings  produced  by  glacier  movements  now  to  be 
seen,  yet  this  is  in  no  way  remarkable ;  for  the  bed-rock  is  of  too 
soft  a  character  to  have  preserved  any  such  evidence.  The  presence 
of  the  large  jasperoid  boulders  is  confirmatory.  They  do  not  belong 
to  the  locality,  since  no  similar  rock  is  found  nearer  than  the  Blue 
Mountains  or  Tapanui,  25  miles  northwestward.  They  were  car- 
ried down  by  the  ice.  The  character  of  a  large  portion  of  the  ma- 
terial forming  the  deposit  similarly  indicates  that  it  was  not  brought 
down  in  or  by  a  stream  of  water,  but  as  the  rocky  freight  of  a 
glacier.  A  large  part  of  the  wash  consists  of  angular  fragments  of 
quartz,  as  well  as  of  pieces  of  the  quartzose  schist-rock,  which  are 
not  rounded.  The  agency  which  eroded  the  depression  in  which  the 
auriferous  material  lies  was  assisted  by  the  structure  of  the  rock  at 
this  particular  point.  I  have  no  doubt  that  the  N.E.  bounding- wall 
of  the  deposit  forms  the  line  of  a  fault,  and  that  the  reason  of  the 
formation  of  the  rocky  basin  at  this  particular  spot  is  to  be  found  in 
the  fact  that  the  schist  had  been  crushed  by  the  movements  accom- 
panying faulting.  Of  this  the  X.E.  wall,  its  smooth  face,  and  its 
continuation  under  the  opposite  rim-rock,  together  with  the  crushed 
condition  of  the  S.W.  country  are  ample  evidence.  The  line  of 
fault  is  not  parallel  to  the  course  of  the  lead ;  the  two  meet  between 
Munro's  and  Gabriel's  Gully;  and  so  explain  the  enlargement  at 
that  point  of  the  receptacle  of  the  ore-deposit. 

This  explains  the  natural  selection  of  this  particular  place  as  the 
locus  of  the  deposit.  To  proceed  further,  the  glacier  in  its  slow 
downward  progress  to  the  sea  is  temporarily  arrested  by  the  softer 
rock  which  it  here  encounters  much  in  the  same  way  as  a  runner  is 
retarded  in  crossing  a  ploughed  field.  This  arrest  allowed  the  ac- 
cumulation of  a  terminal  moraine,  which,  protecting  the  rock  on 


30  THE   GOLD-FIELDS   OF   OTAGO. 

which  it  lay,  assisted  the  tendency  of  the  ice  to  erode  the  softer 
schist;  where  the  terminal  moraine  at  one  time  lay,  we  now  find  the 
rocky  bar  shown  in  Fig.  2.  A  hollow  was  scooped  out.  This  was 
in  early  Eocene  days.  A  little  later,  that  subsidence  took  place 
which  preceded  the  deposition  of  the  Oamaru  series.  This  caused 
the  retirement  of  the  glacier,  or  more  accurately,  the  melting  away 
of  its  lower  portion.  The  rocky  basin  which  had  been  scooped  out 
by  the  ice  now  became  a  fresh-water  lake,  with  its  upper  end  still 
guarded  by  the  glacier.  The  ice  which  broke  away  from  the  foot  of 
the  glacier  bore  with  it  the  large  boulders  of  jasperoid  which  had 
been  brought  down  from  Tapanui.  This  and  other  material  was 
borne  across  the  lake,  to  fall  eventually  upon  its  bottom  as  the  ice- 
floes melted.  In  the  meantime,  up  above,  the  glacier  continued  to 
plough  through  the  soft  quartzose  schists  and  sent  down  a  golden 
tribute,  derived  from  the  lode-formations  which  it  cut  through. 
The  fine  flakes  of  gold  were  accompanied  with  micaceous  mud  and 
angular  bits  of  quartz,  all  to  be  deposited  in  the  capacious  hollow  of 
the  lake.  Thus  the  rocky  basin  became  gradually  filled  up  with 
confused  layers  of  big  jasperoid  boulders,  quartz-gravel  and  bluish 
mud,  the  gold  sifting  its  way  to  the  lower  portions.  The  subsidence 
continuing,  and  with  it  the  slow  retirement  of  the  glacier,  and  the 
lake  being  nearly  full  of  detritus,  it  became  a  morass.  Vegetation 
took  root  and  flourished  for  a  brief  period.  A  time  of  flood  due  to 
excessive  thaw  brought  down  a  volume  of  water  bearing  the  sand 
and  gravel  which  covered  the  vegetation.  Being  thus  protected 
from  the  air,  the  reeds  of  the  morass  became  the  lignite  of  to-day. 

A  river  linking  a  series  of  small  lakes,  of  which  the  Blue  Spur 
was  one,  now  flowed  along  the  course  of  the  present  alluvial  lead. 
Additional  material  was  deposited  in  some  places,  while  material  was 
removed  in  others.  In  the  middle  of  the  Eocene  period,  the  eleva- 
tion of  the  land  culminated  and  changed  the  drainage-system  of  the 
district.  In  Miocene  times,  the  Clutha  and  its  tributaries  began 
to  flow  across  the  line  of  the  Blue  Spur  lead.  That  erosion  then 
commenced  which,  in  the  cutting  out  of  Munro's,  Gabriel's  and 
Weatherstone's  gullies,  left  the  gravel-deposit  as  a  part  of  a  dividing 
ridge. 

Reference  has  been  made  by  Hutton  to  the  fact  that  certain  of  the 
Eocene  beds  contained  gold  in  order  to  explain  its  occurrence  in  the 
Blue  Spur  deposit.  This  is  not  needed.  The  examination  of  the 
material  composing  the  conglomerate  shows  that  the  larger  part  is 
derived  from  the  degradation  of  the  primary  schists.  The  grinding 


THE   GOLD-FIELDS   OF   OTAGO.  31 

by  the  ice  of  these  soft  rocks  formed  the  mud  which  is  now 
"cement."  It  was  from  the  quartzose  folia  that  was  derived  the 
coarse  gravel,  and,  finally,  it  was  the  gold  which  elsewhere  to-day  is 
found  in  the  lodes  and  even  in  the  rocks  of  the  Wanaka  series,  which 
made  the  Blue  Spur  not  only  a  geological  study  but  also  a  very 
valuable  gold-mine. 

CONCLUSION. 

The  consideration  of  the  gold-deposits  of  Otago,  whether  in 
lodes  or  alluvium,  is  intimately  connected  with  the  study  of  the 
quartzose  schists  which  are  the  characteristic  country-rock  of  the 
one  and  the  bed-rock  of  the  other.  In  many  respects  these  rocks 
are  remarkable.  Their  extent  and  unbroken  continuity  have  been 
referred  to;  allusion  has  also  been  made  to  the  many  interesting 
physiographical  studies  which  they  offer;  and  it  now  remains  to 
briefly  refer  again  to  their  auriferous  character. 

That  the  bulk  of  the  gold  of  the  extensive  alluvium  of  Otago 
came  from  the  degradation  of  the  known  lodes,  I  do  not  believe. 
The  mere  proportion  of  the  known  extent  of  the  one  to  that  of  the 
other  may  be  an  insufficient  basis  for  such  a  conviction,  for  in  this 
country,  as  in  other  comparatively  new  regions,  the  mineral  de- 
posits are  only  in  an  infancy  of  development ;  yet  this  fact  has  some 
weight.  The  chief  evidence  comes,  however,  from  the  known  rela- 
tions of  the  lodes  to  the  country-rock,  and  from  the  character  of  the 
alluvial  gold  itself. 

It  is  not  necessary  to  recapitulate  the  observations  made  on  the 
lodes ;  how  they  are  for  the  most  part  ore-channels,  the  auriferous 
filling  of  which  shades  off  into  the  surrounding  country,  as  regards 
both  gold-contents  and  structure.  The  gold  of  the  alluvium  has 
not  that  shotty  character  familiar  to  the  digger  of  Australia  or  Cali- 
fornia. An  exception  must  be  made  of  the  small  placer-deposits  of 
some  of  the  mountain  streams,  the  nuggety  gold  of  which  is  easily 
traceable  to  its  source  in  the  neighboring  quartz-veins.  Such  gold 
is,  however,  quite  exceptional,  and  altogether  of  a  character  different 
from  that  of  the  great  fluviatile  and  lacustrine  deposits  of  the  Clutha 
and  Shotover,  the  wealth  of  which  is  contained  in  the  very  fine 
flaky  gold,  which  is  like  bran  and  notable  for  its  uniformity  of  size 
and  wide  distribution.  It  has  a  character  making  it  easy  of  recog- 
nition among  samples  coming  from  other  districts.  It  is  also  re- 
markable that  quartz  stones  showing  gold  are  of  very  rare  occur- 
rence at  the  Blue  Spur  or  in  the  gravel-deposits  of  the  Clutha  and 


32  THE   GOLD-FIELDS    OF   OTAGO. 

Shotover.  The  gold  came,  I  believe,  as  did  the  gravel  through 
which  it  is  distributed  and  the  cement  in  which  it  is  often  imbedded, 
not  from  the  few  comparatively  insignificant  quartz-lodes,  but  from 
the  great  mass  of  the  quartzose  schists.  The  quartz  folia  which 
form  the  characteristic  feature  of  the  schists  of  Otago  are  known  in 
places  to  carry  gold  far 'outside  the  limits  of  any  of  the  particular 
lode-channels  which  also  traverse  them.  One  could,  with  perfect 
reason,  regard  the  whole  belt  of  quartzose  schists  as  one  large  bed- 
vein,  in  which  the  lodes  now  worked  are  merely  small  cross-veins, — 
a  large  gold-vein,  through  which  for  ages  the  glaciers  have  ploughed 
an  easy  way,  cutting  furrows  from  which  the  quartz  and  schist  have 
been  swept  by  wind  and  rain  into  the  swift  waters  of  the  Clutha  and 
Shotover,  to  be  laid  down  by  them  in  the  form  of  the  great  banks 
and  terraces  of  gold-bearing  alluvium,  which  to-day  are  the  chief 
depositories  of  the  mineral  wealth  of  Otago. 


NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors, 
or  communications  for  publication  as  "  Discussion,"  or  independent 
papers  on  the  same  or  a  related  subject,  are  earnestly  invited. 


Subject  to  Revision. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OP  MINING  ENGINEERS.] 


ALLUVIAL  MINING  IN  OTAGO. 

BY  T.   A.    RICKARD,   DENVER,   COLORADO. 
(Lake  Champlain,  Plattsburgh,  Meeting,  June,  1892.) 

Ix  a  previous  contribution  some  description  was  given  of  the  oc- 
currence of  the  auriferous  alluvium,  extensive  deposits  of  which  lie 
among  the  highlands  of  the  province  of  Otago,  New  Zealand.  The 
present  paper  will  describe  some  of  the  methods  by  which  that  allu- 
vium is  exploited. 

The  alluvial  mining  of  New  Zealand  is  not  yet  hindered  by 
"debris  legislation."  The  mines  are  for  the  most  part  situated  in  a 
country  of  little  agricultural  value,  and  large  rivers  with  rapid  cur- 
rents act  as  tailings  conveyors.  In  time,  however,  steps  will  have 
to  be  taken  to  restrict  the  discharge  into  the  Clutha  of  the  tailings 
which  are  slowly  raising  the  river-bottom. 

The  methods  of  California  have  been  followed  in  Otago  with  such 
alterations  as  peculiar  local  conditions  require.  The  distinctive 
feature  of  the  alluvial  mining  of  Otago  is  the  prominence  given  to 
the  hydraulic  elevator.  The  all-important  factor  in  this  form  of 
mining  is  the  control  of  an  abundant  water-supply  at  a  suitable 
height  above  the  level  where  it  is  to  be  utilized;  and  in  this  respect 
the  gold-fields  of  the  south  island  of  New  Zealand  are  most  favora- 
bly situated,  the  low  level  of  the  snow-line  insuring  a  splendid  sup- 
ply throughout  the  year,  and  under  a  pressure  which,  in  practice,  is 
only  limited  by  the  strength  of  the  plant  and  the  expense  incurred  in 
its  installation.  This  is  in  marked  contrast  with  the  gold-fields  of 
the  Australian  continent,  which  have,  on  the  other  hand,  a  magnifi- 
cent supply  of  the  best  mining-timber. 

Next  to  the  hydraulic  elevator  in  importance  comes  the  dredge, 
the  use  of  which  in  Otago,  under  several  forms,  is  rapidly  extend- 
ing in  the  exploitation  of  the  river-bottoms  and  sea-beaches. 

THE  HYDRAULIC  ELEVATOR. 

This  machine,  which  is  destined  to  have  an  ever-widening  field  of 
usefulness,  consists  essentially  of  an  inclined  pipe,  at  the  bottom  of 
which  a  jet  of  water  under  heavy  pressure  is  allowed  to  play,  and 


ALLUVIAL   MINING   IN    OTAGO. 


ALLUVIAL    MINING    IN   OTAGO.  3 

by  its  action  propel  through  the  pipe  the  gravel  and  water  which 
enter  at  its  lower  opening.  The  action  of  the  jet  at  the  foot  of  the 
elevator  is  not  limited  to  the  direct  force  of  the  water  liberated  under 
a  heavy  pressure,  but  is  also  in  a  large  measure  aided  by  the  strong 
suction  induced  by  the  vacuum  created  by  the  upward  rush  of  the 
water.  This  suction  is  also  of  importance  in  that  it  draws  the  gravel 
through  the  opening  and  thereby  does  the  feeding.  Originally  the 
pipe  of  the  elevator — called  the  uptake  or  discharge-pipe — was  sepa- 
rate from  the  jet  or  nozzle  which  was  directed  up  it;  but  in  the 
newer  forms  of  the  machine  the  two  are  combined  into  one  compact 
casting.  Not  only  has  this  modification  made  the  elevator  a  more 
complete  machine,  but  by  diminishing  the  unnecessary  distance  be- 
tween the  jet  and  the  opening  which  admits  the  gravel,  it  has  allowed 
a  greater  advantage  to  be  derived  from  the  suction  induced  by  the 
rapid  passage  of  the  water. 

By  reference  to  Figs  1  to  5  the  following  description  will  be  under- 
stood. The  bottom  of  the  elevator  has  a  bracket,  called  the  "  foot," 
which  is  placed  upon  the  bed-rock  upon  which  lies  the  gravel  which 
it  is  intended  to  raise.  The  water  and  gravel  enter  at  the  "  hopper  " 
or  intake  C,  being  drawn  in  by  the  suction  caused  by  a  powerful  jet 
of  water  which  passes  through  the  "jet"  or  "  nozzle"  B  and  im- 
pinging upon  the  entering  gravel  and  water  sweeps  them  up  the  ele- 
vator or  "  uptake  "  pipe  D.  At  the  upper  end  of  this  pipe  the  gravel 
is  deflected  by  the  "  striking-plate  "  S  (Fig.  1)  and  proceeds  down 
the  series  of  sluice-boxes  arranged  at  a  gentle  incline.  These  sluice- 
boxes  are  provided  along  their  bottom  with  riffles  and  other  con- 
trivances to  arrest  the  gold  carried  in  the  gravel,  from  which  it 
separates  by  the  action  of  gravity. 

Gravel  and  water  hurled  with  such  velocity  as  belongs  to  a  jet 
under  a  head  of  several  hundred  feet,  must  produce  great  wear  and 
tear  upon  any  surface  against  which  they  impinge.  The  greatest 
amount  of  friction  takes  place  at  the  lower  part  of  the  uptake-pipe, 
called  the  "  throat "  (E).  This  is  narrowed  so  as  to  prevent  the 
scattering  of  the  jet  and  the  consequent  decrease  of  its  effectiveness. 
A  strong  removable  casting  called  the  "  liner,"  is  here  inserted.  It 
increases  gently  in  diameter  from  its  lower  end  upward.  See  Figs. 
2  and  5.  A  liner  three  inches  thick  lasts  about  six  weeks. 

Passing  up  the  elevator  pipe,  the  gravel  meets  the  "  striking- 
plate."  This  is  a  heavy  piece  of  iron  2  feet  square  and  3  inches 
thick.  It  should  last  from  two  to  three  months;  but  a  defective 
casting  will  be  broken  in  a  few  hours.  The  force  of  the  ejected 


ALLUVIAL    MINING    IN   OTAGO. 


gravel  is  not  all  expended  upon  the  striking-plate,  hence  the  head 
sluice-box,  the  sides  of  which  are  usually  raised  to  2J  feet,  is  lined 
with  iron  plate  (No.  12  boiler-plate),  to  protect  the  wood-work. 


Fig.  5. 


,8  holei 


J 

D 

E 

,  6  holes  for  &  bolts 


Outer  nozzle  bored — 
Out  and  Inside  noz- 
zle turned  to  fit 


THE  ATMOSPHERIC   NOZZLE 

FITTED  TO  THE 

HYDRAULIC   ELEVATOR 


When  properly  handled,  the  elevator  is  a  most  effective  machine, 
raising  a  cubic  yard  or  1-J  tons  of  gravel  per  minute,  together  with 


ALLUVIAL    MINING   IN    OTAGO.  5 

a  large  volume  of  water.  Thus  it  not  only  lifts  the  gravel  but  also 
acts  as  a  pump  in  getting  rid  of  the  water  used  in  breaking  down 
the  face  of  the  wash.  Its  usefulness  in  the  latter  capacity  is  highly 
important  to  those  engaged  in  the  working  of  claims  the  bedrock 
of  which  may  be  below  the  drainage-level.  It  is  this  feature  of  the 
machine  which  has  rendered  it  of  special  service  in  the  alluvial 
mines  bordering  upon  the  rivers  of  Otago. 

The  first  introduction  of  the  hydraulic  elevator*  in  Otago  was 
made  by  Cranston  and  Perry  in  1882.  John  Perry  did  a  good 
deal  of  experimental  work  about  that  time,  and  in  1884  inaugurated 
the  first  successful  working  at  the  Blue  Spur  in  Gabriel's  Gully.f 

The  Blue  Spur. — This  ranks  among  the  first  of  the  alluvial  mines 
of  New  Zealand.  The  English  company  (the  Blue  Spur  and  Gabriel's 
Gully  Consolidated  Mining  Company  Limited),  which  was  formed 
by  the  amalgamation  of  a  large  number  of  miners'  claims,  is  at 
present  only  working  the  tailings,  of  which  there  is  an  enormous 
body  lying  in  Gabriel's  Gully.  These  tailings  have  a  maximum 
thickness  in  the  center  of  the  gully  of  72  feet,  while  the  face  now 
being  worked  is  59  feet  high.  They  are  estimated  to  cover  an  area 
of  120  to  130  acres,  of  which  the  company  owns  23  acres. 

The  original  deposit  (described  in  my  former  paper)  was  worked 
in  the  first  instance  by  numerous  small  parties  of  miners  by  means 
of  ground-sluicing  supplemented  with  the  crushing  of  the  larger 
lumps  of  cement  in  small  stamp-mills,  the  big,  hard  boulders  being 
picked  out  previously  by  hand  and  thrown  to  one  side.  I  could  not 
find  that  any  gold  was  got  in  the  large  quartz  pebbles;  it  was  al- 
most entirely  confined  to  the  blue  cement  forming  the  bulk  of  the 
material.  This  cement  was  very  hard,  and  the  gold  now  obtained 
is  due  in  large  measure  to  the  disintegration  of  the  solid  lumps  left 
in  the  tailings. 

The  accompanying  sketch,  Fig.  6,  will  indicate  the  appearance  of 
the  workings  and  the  method  of  exploitation.  To  the  left  is  seen 
the  nozzle  or  giant,  the  diameter  of  the  brasses  being  2J  inches, 
supplied  by  a  10-inch  pipe  carrying  water  under  a  head  of  400  feet. 
The  water-race,  fed  from  the  Waipori  river,  is  31  miles  long.  The 

*  Also  called  "  tailings  elevator  "  at  Ballarat,  "ejector  "  and  "  lift"  in  Otago. 

f  Since  writing  the  above,  my  attention  has  been  drawn  to  a  description  by  Dr. 
R.  W.  Raymond  (Trans.,  viii.,  254),  of  a  dredge  invented  by  Gen.  Roy  Stone,  in 
which  a  jet  under  heavy  pressure  is  used  to  break  the  material  under  water  (as  a 
similar  nozzle  does  on  land),  and  the  material  so  excavated  is  sent  to  the  surface  by 
the  action  of  another,  larger  jet,  working  inside  a  pipe. 


ALLUVIAL   MINING   IN   OTAGO. 


ALLUVIAL   MINING   IN   OTAGO.  7 

nozzle  is  represented  as  playing  upon  a  face  of  tailings  about  59  feet 
high,  separated  from  the  bed-rock  by  6  to  8  feet  of  black  silt,  in 
which  are  the  layers  of  wash  which  were  worked  in  the  early  days, 
as  is  evidenced  by  the  timbers  of  old  shafts  and  drifts  which  are 
occasionally  displaced  by  the  water.  Immediately  above  the  lower 
bed  of  alluvium  was  the  site  of  the  old  township  which  sprung  up 
at  the  time  of  the  rush  of  1861,  now,  however,  completely  buried 
under  50  to  60  feet  of  tailings.  Its  former  position  is  proved  by  the 
miscellaneous  assortment  of  articles*  which  the  sluice-boxes  collect. 
These  occur  imbedded  in  the  silt  together  with  a  large  quantity  of 
lead  in  the  form  of  shot,  reminders  of  that  eccentric  fusilading  which 
often  characterizes  a  mining  camp  in  its  early  stages.  The  gold 
obtained  from  this  ground  is  usually  coated  with  quicksilver. 

The  nozzle  is  about  50  yards  from  the  first  elevator,  which  is 
shown  next  to  the  right.  The  wash  is  driven  by  the  water  from  the 
nozzle  into  the  opening  or  hopper  of  the  elevator,  the  man  in  charge 
removing  the  larger  boulders  which  tend  to  choke  it.  The  dimen- 
sions are:  hopper,  14;  jet,  2;  throat,  6J,  and  uptake  pipe  15  inches 
in  diameter.  The  water  which  does  the  work  comes  under  a  pres- 
sure of  430  feet  through  a  10-inch  pipe.  The  material  is  lifted  15J 
feet,  and,  impinging  upon  the  striking-plate,  passes  down  the  sluice- 
boxes  which  are  3  feet  wide  and  in  lengths  of  12  feet,  with  a  grade 
of  9  inches  in  12  feet.  Two  hundred  and  forty  feet  further  to  the 
right  is  the  second  elevator,  which  raises  the  gravel  again,  this  time 
through  a  vertical  height  of  56  feet  through  a  pipe  65  J  feet  long, 
inclined  at  an  angle  of  58°  45'.  The  second  elevator  has  /iimen- 
sions  similar  to  those  of  the  first,  and  delivers  the  material  into 
sluice-boxes  having  a  grade  of  9J  inches  in  12  feet,  whence  it  is 
finally  deposited  on  the  tail  ings- heaps,  most  of  the  water  finding  its 
way  into  the  main  drain  along  the  true  bottom  of  the  gully.  One 
of  the  shafts  connecting  with  the  drain  is  shown  to  the  middle  right 
of  the  sketch.  In  the  immediate  foreground  is  the  pressure-pipe  of 
the  first  elevator.  The  smaller  pipe  shown  near  the  elevator  itself 
is  only  brought  into  use  in  cleaning  up  the  sluice-boxes.  The  face 
of  the  bank  of  tailings  is  kept  up  by  an  arrangement  of  fascines, 
which  are  roughly  indicated  to  the  right,  above  the  shaft. 

All  the  gold  saved  is  obtained  from  the  run  of  sluice-boxes  be- 

*  Coins,  gold  and  silver,  rings,  copper  rivets,  nails,  etc.  Among  other  curiosi- 
ties, the  manager  showed  me  several  nuggets  which  had  been  obtained  in  cleaning 
up.  These,  judging  by  the  character  of  the  gold,  were  obtained  in  some  other  dis- 
trict, very  probably  Ballarat,  and  lost  here. 


ALLUVIAL    MINING   IN   OTA  GO. 


ALLUVIAL   MINING   IN   OTAGO.  9 

tween  the  two  elevators.  These  boxes,  as  already  stated,  have  a 
general  grade  of  9  inches  in  12  feet,  but  the  last  two  or  three  have  12 
to  14  inches.  The  bottoms  are  covered  with  cocoanut  matting, 
over  which  are  placed  riffles  of  angle-iron  riveted  to  angle-iron. 
The  end  boxes  are  provided  instead  with  f-inch  perforated  J-inch  iron 
plate. 

The  details  of  the  plant  are  shown  in  Figs.  7  to  11.*  The  ele- 
vator is  not  of  the  best  type ;  the  manager  does  not  recommend  it. 
The  T-piece  and  blind  flange  mean  an  unnecessary  resistance  to  the 
water.  The  best  form  approximates  that  to  be  described  later  on  as 
in  use  at  some  of  the  newer  mines  on  the  Clutha  river.  The  con- 
nection between  the  pressure-pipe  and  the  elevator  should  take  place 
along  a  greater  angle,  since  the  less  the  deflection  of  the  water  the 
greater  the  efficiency  obtained. 

The  striking-plate  is  a  casting  24  by  24  inches  by  3  inches  thick. 
The  head-box  is  lined  with  No.  12  boiler-plate  to  protect  the  wood- 
work against  the  stones  deflected  from  the  striking-plate. 

It  is  not  found  necessary  to  use  deflectors  with  the  nozzle.  The 
usual  feathers — shown  in  section  A  B,  Fig.  10 — for  keeping  the 
water  from  scattering,  are  provided.  The  ball-joint  with  pin  per- 
mits the  vertical  movement  of  the  director.  Instead  of  the  universal 
joint  which  is  so  apt  to  get  jammed,  a  large  holding-down  bolt  regu- 
lates the  horizontal  motion. 

The  manager  of  the  Blue  Spur  has  designed  a  new  form  of  riffle. 
The  angle-iron  on  angle-iron  is  a  riffle  which  entails  a  great  waste  of 
material,  to  avoid  which  a  reversible  form  would  be  advantageous. 
This  is  shown  in  Fig.  12.  The  eight  bars  are  not  riveted  each  sep- 
arately, as  is  usual,  but  rest  upon  mortices  or  recesses  in  the  two 
lateral  retaining-bars,  and  are  kept  in  position  by  the  two  bolts  as 
indicated.  In  this  way,  when  the  edge  of  one  side  of  the  riffle  bars 
becomes  worn  out,  it  is  but  the  work  of  a  few  minutes  to  loosen  the 
bolts  and  reverse  the  bars.  With  such  an  arrangement  it  is  neces- 
sary that  the  bars  should  be  accurately  cut,  otherwise  they  do  not 
remain  firmly  in  place. 

While  the  plant  at  the  Blue  Spur  is  by  no  means  the  best  in  Otago, 
yet  the  following  record,  given  to  me  by  the  manager,  shows  that 
very  good  work  is  done  here. 

In  working  a  face  of  tailings,  55  feet  high,f  26,929  cubic  yards 

*  Traced  from  the  original  of  Mr.  Howard  Jackson,  the  Manager,  who  kindly 
granted  permission. 

f  The  tailings  have  consolidated  by  reason  of  the  cement  of  the  original  de- 
posit, which  they  contain,  and  present  the  character  of  ordinary  wash. 


ALLUVIAL   MINING   IN   OTAGO. 


11 


were  raised  and  dumped  a  height  of  87.8  feet  in   a  period  of  680 
hours. 

The  yield  obtained  was  115  ounces,  11  pennyweights,  16 

grains,  worth £433.8.9 

The  working  cost  included  3  men,  .         .        .        £89.5.0 

Two  liners  worn  out,         .....  10.4.0 

Add  to  this  for  depreciation  of  plant,  manage- 
ment, etc., 99.9.0. 

The  total  cost  was, 198.18.0 

Leaving  a  profit  of, £234.10.9 

The  value  of  the  material  was  5.6  pence  per  yard  or  3}  pence  per 
ton. 

The  cost  of  working  was  1.77  pence  per  cubic  yard  or  7.78  pence 
per  ton. 

F'g.  12. 


CROSS-SECT.IO'N  A.A. 


RIFFLE  WITH  REVERSIBLE  BARS 


CROSS-SECTION   B.B. 


The  water  used  with  2  elevators  and  1  nozzle,  was  as  follows : 

No.  1  Elevator,  450-ft.  head.  Pressure  1 93  pounds  per  square 
inch.  8f  sluice-heads.* 

No.  2  Elevator,  375-ft.  head.  Pressure  164  pounds  per  square 
inch.  10  sluice-heads. 

Nozzle,  375-ft.  head.  Pressure  164  pounds  per  square  inch.  3f 
sluice-heads. 

The  gold  won  from  the  sluice-boxes  was  97  ounces,  16  penny- 
weights, 18  grains,  worth  £366  17s.  Wd. 

Pickings  from  the  "reef"  or  rim-rock,  17  ounces,  14  pennyweights, 
22  grains,  worth  £66  10s.  llcZ. 

The  latter  gold  was  imbedded  in  the  crevices  of  the  schist  which 
forms  the  bed  rock. 

f  A  sluice-head  of  water  equals  theoretically  1  cubic  foot  per  second  ;  in  practice 
it  is  usually  calculated  at  50  cubic  feet  per  minute. 


12 


ALLUVIAL    MINING   IN   OTAGO. 


Considering  that  this  work  was  done  under  the  disadvantages  of 
a  much  worn  and  by  no  means  first-rate  plant,  it  is  needless  to  em- 
phasize the  good  results  obtained  in  so  far  as  economy  of  handling 
is  concerned. 

It  so  happens  that  at  the  North  Bloomfield  claim,  in  California,  the 
elevator  was  used  under  conditions  which  render  interesting  a  com- 
parison. There  a  more  elementary  type  of  elevator  was  in  use,  the 
jet  not  being  a  part  of  the  machine  itself,  not  even  inserted  inside 
the  mouth-piece,  but  so  placed  as  to  shoot  up  the  line  of  the  elevator 
pipe.  There  one  elevator  lifted  gravel  a  vertical  height  of  87  feet ; 
here  two  elevators  raised  the  material  in  two  lifts  of  31.8  and  56 
feet  respectively  to  a  total  height  of  87.8  feet.  At  the  Blue  Spur  a 
nozzle  with  a  head  of  375  feet  and  delivering  3f  sluice-heads  (or 
5400  cubic  feet  per  24  hours)  did  the  work  of  breaking  down  the 
bank,  which  at  the  North  Bloomfield  was  done  by  a  stream  of  800 
miners'  inches  (or  1,  784,000  feet  per  24  hours),  under  a  head  of 
450  feet.  Other  figures  are  as  follows : 


Height  of  face  of  gravel, 
Diameter  of  elevator-pipe,  . 

At  the  throat, 

Diameter  of  jet,     .        , 
Water  used  in  the  elevators, 


Under  a  head  of  .       r« 

Capacity  of  the  plant  per  24 

hours,        .    ''   .    '    .  'l{".r 


Blue  Spur. 
55  feet 
15  inches. 
6£  inches. 
2  inches. 
18|  sluice-heads 
or  27,000  cu- 
bic   feet    per 
24  hours. 
410  feet. 

North 
Bloomfield. 

135  feet. 
22  inches. 
14  inches. 
6£  inches. 
1400  miners'  inches 
or  3,122,000  cubic 
feet  per  24  hours. 

530  feet. 

1000  cubic  yards.   2400  cubic  yards. 


The  wear  and  the  tear  at  the  North  Bloornfield  was  found  so 
excessive  that  the  use  of  the  elevator  was  discontinued.  Under  the 
conditions  which  obtained  there,  nothing  less  than  25  cents  per  cubic 
yard  would  pay.* 

The  Island  Block. — A  modern  plant  may  be  seen  at  the  Island 
Block,  where  three  elevators  are  at  work.  The  nature  of  the  deposit 
was  described  in  my  former  paper  as  an  old  channel  of  the  river 
Molyneux  or  Clutha.  At  the  time  of  my  visit,  the  face  of  wash  was 
40  to  51  ft.  high,  the  top-gravel  being  poor  but  not  absolutely  bar- 
ren, while  the  "  pay"  consisted  of  the  lowermost  10  to  15  feet.  The 


*  This  information  I  owe  to  Mr.  W.  H.  Kadford,  formerly  superintendent  of 
North  Bloomfield. 


ALLUVIAL   MINING   IN   OTAGO.  13 

gold  is  accompanied  by  a  large  amount  of  fine  black  iron  sand,  the 
bulk  of  which,  on  cleaning  up,  is  collected  with  a  magnet.  The 
nuggets  found  in  alluvial  mining  elsewhere  are  unknown  here,  for 
the  precious  metal  occurs  in  rounded  flakes,  of  a  fairly  uniform  size 
and  rarely  more  than  T35  inch  in  diameter.  The  wash  contains 
numerous  pebbles  of  what  the.  miners  call  "  black  maori,"  a  sort  of 
siliceous  wad,*  resulting  from  the  hydration  and  oxidation  of  rho- 
donite, the  silicate  of  manganese.  The  transition  can  sometimes 
be  observed.  The  quartzose  schists  form  the  bed-rock,  but  are  not 
represented  by  any  large  boulders,  their  easy  degradation  having 
produced  the  small  angular  quartz  stones,  the  sand  and  the  dark 
blue  silt  which  form  so  large  a  proportion  of  the  wash. 

A  plant  of  unusual  excellence  has  been  erected  here.  The  bed- 
rock being  below  the  level  of  the  river,  the  wash  is  raised  by  hy- 
draulic elevators  into  sluice-boxes,  a  lift  of  40  to  60  ft.  To  do  this 
work,  water  is  taken  from  a  stream  named  the  Fruid  burn,  and  con- 
ducted through  pipes  of  lap-welded  steel,  until  it  arrives  at  the 
elevators,  where  it  comes  under  a  head  of  760  feet.  Starting  from 
the  penstock  or  pressure-box  with  a  double  main,  each  branch  having 
a  diameter  of  16  J  inches,  the  water,  after  17  chains,  is  delivered 
into  a  single  pipe  which  for  27  chains  has  a  diameter  of  16 \  inches, 
to  be  reduced  to  a  pipe  15  inches  diameter,  which  conducts  it  to  the 
immediate  vicinity  of  the  heading  when  a  final  reduction  to  9  inches 
diameter  takes  place.  The  discharge  or  uptake  pipe  of  the  elevator 
is  15  inches  and  the  jet  is  2J.  The  material  lifted  per  elevator 
varies  with  the  character  of  the  gravel  from  30  to  40  tons  per  hour. 
The  lap-welded  steel  pipes  are  all  manufactured  in  England.  Their 
thickness  varies  from  J  to  ^  of  an  inch,  the  greater  thickness  is 
found  to  make  them  too  heavy  and  the  lesser  is  far  more  than  equal 
to  any  strain  to  which  they  may  be  subjected.  They  are  said  to  have 
been  tested  up  to  1000  pounds  per  square  inch  previous  to  being 
sent  out.  The  price  of  these  pipes  varies  from  8s.  2d.  per  foot  for 
15-inch  pipes  to  4s.  Sd.  for  11  inch  ;  but  the  average  has  been  about 
6s.  Qd.  for  the  15- inch  pipes,  of  which  the  greatest  length  has  been 
used.  This  figure  should  not  prevent  their  extensive  use  on  the 
part  of  companies  desirous  of  erecting  a  first-class  permanent  plant. 

All  the  joints  are  faced  with  the  lathe  and  the  pipes  are  in  18  feet 
lengths.  Of  course  such  lap-welded  pipes  severely  test  the  joints, 
the  excess  of  pressure  on  which  is  not  relieved,  as  is  ordinarily 

*  As  was  pointed  out  to  me  by  Professor  G.  H.  F.  Ulrich,  now  of  the  University 
of  Otago. 


14 


ALLUVIAL    MINING    IN    OTAGO. 


the  case,  by  leakage  along  rivets.  The  pattern  adopted  is  the 
Kimberly  (see  Fig.  13). 

A  is  a  loose  angle-iron  flange  which  is  slipped  on  before  the  ring 
B  is  shrunk  on  to  the  pipe.  This  arrangement  is  very  convenient, 
since  the  bolt-holes  in  the  flanges  can  be  made  to  fit  without  all  the 
trouble  of  turning  a  length  of  pipe.  .  The  drawback  to  this  form  of 
joint  consists,  however,  in  the  fact  that  for  rough  country  it  is  not 
well  adapted,  since  with  any  movement  the  shoulder  is  apt  to  slip 
out  of  its  recess,  producing  a  leak.  For  fairly  straight,  permanent 
lines  it  is  most  desirable. 

The  wash  is  thrown  by  the  elevators  into  sluice-boxes  of  Kauri 
pine,  3  feet  wide,  1  foot  deep,  and  in  lengths  of  12  feet.  Old  40- 
pound  rails  are  used  to  support  them.  (See  Fig.  14.)  They  are 


Fig.  13. 


Sackir 


Fig.  14. 


T 

LLHr" 

[W         1 

1 

*F>                     Sheet 

Iron               ^             ]lV 

s 

OC^J^,     !   Rail 

KlMBERLEY  FLANGE 


SLUICE-BOXES 

lined  with  thin  sheet-iron,  and  set  at  a  grade  varying  with  the  mate- 
rial treated,  the  average  being  8  inches  per  12  feet.  With  the 
"  stripping"  or  uppermost  layers  of  "  wash,"  this  is  increased  to  9 
inches ;  and,  on  the  other  hand,  the  last  few  boxes  of  a  series  are 
inclined  at  from  7  to  7J  inches  only.  Sacking  (common  bags,  ripped 
up)  is  put  along  the  bottom  of  the  upper  boxes,  underneath  the  riffle 
bars.  The  riffles  are  of  the  usual  form,  angle-iron  riveted  to  angle- 
iron.  After  a  varying  distance — 100  to  150  feet — of  ordinary  riffles 
there  succeeds  a  series  of  "  under-currents"  or  false  bottoms.  These, 
like  the  "  grizzly, "  or  sizing-bars  of  a  stamp-mill,  serve  to  separate 
the  larger  boulders  from  the  finer,  richer  wash.  In  their  arrange- 
ment a  set  of  iron-bar  riffles  follows  the  ordinary  angle-iron  riffle  ; 
that  is  to  say,  the  first  bar  (of  a  set  of  flat  iron  bars,  T^-  inch  apart) 
is  placed  upon  the  last  bar  of  angle-iron,  so  as  to  form  a  sieve  or 
false  bottom  through  which  most  of  the  fine  wash  finds  its  way. 

The  false  bottom  is  placed  at  a  less  inclination  than  the  sluice-box, 
and  as  a  consequence,  the  depth  increases  gradually  until,  at  the  end 


ALLUVIAL   MINING   IN   OTAGO.  15 

of  two  12  feet  sluice-boxes  the  distance  between  the  riffles  and  the 
bottom  is  4  inches.  In  this  length  of  24  feet  a  succession  of  vari- 
ous forms  of  riffles  is  employed.  First  come  the  iron-bar  riffles 
already  noted,  for  a  length  of  4  feet.  These  are  found  very  effective 
in  saving  the  fine  gold.  Then  come  two  sheets  of  perforated  iron, 
followed  by  a  '•  blank  "  or  piece  of  plain,  ordinary  iron  plate.  This 
last  is  put  in  to  economize  the  water,  so  much  of  which  would  other- 
wise pass  through  into  the  under-current  that  the  remainder  would 
be  insufficient  to  carry  forward  the  coarser  material.  This  blank  is 
above  the  lower  end  of  the  under-current  and  is  followed  by  a  suc- 
cession of  ordinary  angle-iron  riffles,  to  be  again  followed  with 
another  separation  by  a  second  under-current.  In  this  way  the  wash 
is  sized,  the  coarse  passing  on,  while  the  finer,  more  auriferous  gravel 
is  treated  apart,  in  the  "side-runs  "  to  be  described  later  on. 

The  upper  sluice-boxes  are  lined,  as  I  have  said,  with  ordinary 
sacking;  but  from  the  top  of  the  first  under-current,  cocoanut  mat- 
ting is  substituted,  linen  being  placed  underneath.  The  heavy, 
black  iron-sand  containing  the  gold  finds  its  way  through  the  mat- 
ting which  serves  so  well  to  arrest  it  and  lies  upon  the  linen  which 
covers  the  wood- work.  The  total  length  of  sluice-boxes  varies  from 
200  to  300  feet,  according  to  the  changes  in  the  coarseness  and  rich- 
ness of  the  wash. 

At  the  end  of  the  under-currents,  the  finer  gravel  which  has  thus 
been  separated,  is  diverted  into  "side-runs"  or  "streamers."  These 
are  tables  placed  by  the  aide  of  the  main  line  of  boxes  in  order  to 
effect  the  collection  of  gold.  The  arrangement  comprises  two  tables 
(See  Fig.  15),  each  3  feet  broad  by  24  feet  long,  placed  at  a  grade  of 
10  inches  in  12  feet.  They  are  ordinarily  covered  with  cocoanut 
matting  ;  but  when  washing  the  residues  obtained  from  the  clean-up 
of  the  sluice-boxes,  the  uppermost  4  feet  are  covered  with  green 
baize.  Plush  was  tried  for  this  purpose  but  it  was  found  that  the 
large  quantity  of  black  sand  choked  it.  Of  such  a  pair  of  "side- 
runs,"  one  is  used  at  a  time;  the  inlet  in  the  delivery-box  being 
closed  with  a  piece  of  sheet-iron.  The  material  is  diverted  from  one 
table  to  another  every  two  to  four  hours,  depending  upon  the  fine- 
ness and  richness  of  the  gravel.  In  cleaning  up,  most  of  the  black 
iron-sand  is  removed  while  wet  by  the  use  of  the  magnet ;  after  dry- 
ing, some  of  the  lighter  impurities  are  eliminated  by  blowing.  The 
"blowings"  and  the  iron-sand  are  treated  in  an  amalgamating 
barrel.  This  is  the  only  use  made  of  mercury.  With  the  aid  of 
electric  lights  at  night,  work  goes  on  through  the  twenty-four  hours 
uninterrupted. 


16 


ALLUVIAL    MINING   IN   OTAGO. 


The  Roxburgh  Amalgamated. — Twenty  miles  up  river  from  the 
Island  Block  is  Roxburgh,  where  several  large  hydraulic  plants 
are  at  work.  The  Roxburgh  Amalgamated  Company's  claim 
is  on  the  east  bank,  facing  the  town,  near  the  mouth  of  Teviot 
creek,  and  at  the  lower  end  of  Coal  Creek  flat,  through  the 
western  portion  of  which  the  river  has  cut  its  way.  That  part 
of  the  claim  bordering  upon  the  Clutha  was  originally  worked 
by  the  diggers  with  good  success,  first  by  ground-sluicing  and 
afterwards  by  means  of  a  primitive  dredge.  Though  this  part  of 
the  huge  deposit  which  forms  Coal  Creek  flat  has  been  considered 
the  best,  because  also  the  only  portion  available  for  work,  there  is 
reason  to  believe  that  old  river-channels  may  yet  be  found  in  the 


Fig.  15. 


SIDE-RUNS 

form  of  deep  leads.  At  the  time  when  I  was  in  Roxburgh,  the 
Company  was  engaged  in  opening  up  the  high  terrace ;  but  since 
then  the  manager*  has  discovered  a  lead  some  distance  back  in  the 
flat ;  and  the  elevators  have  made  an  average  monthly  output  of  250 
ounces.  The  gold  is  confined  to  the  lowest  3  feet,  the  top-gravel 
being  absolutely  barren.  This  fact,  only  recently  ascertained,  is 
contrary  to  the  previous  general  opinion  that  these  river-terraces  were 
more  or  less  gold-bearing  through  their  entire  thickness. 

Because  of  its  proximity  to  the  river,  the  claimf  is  subject  to 

*  Mr.  Rene"  Proust,  to  whom  I  am  indebted  for  this  later  information,  as  for 
courtesy  in  every  other  way. 

f  The  New  Zealander  calls  that  part  of  the  claim  which  is  blocked  out  and 
being  worked,  a  "  paddock." 


ALLUVIAL    MINING   IN   OTAGO.  17 

flooding  when  the  river  is  high.  For  this  reason,  at  the  time  of  my 
visit,  only  one  out  of  three  elevators  was  at  work.  The  face  of  wash 
consisted  of  a  barren  over-burden  of  39  feet  lying  upon  20  feet  of 
auriferous  material.  The  59  feet  of  material  thus  necessarily  to  be 
moved  was  handled  by  three  elevators,  each  having  approximately  the 
following  dimensions  : 

Supply  or  pressure-pipe  11,  uptake  or  elevator-pipe  17  inches  in 
diameter.  Liner  narrowed  at  the  throat  to  11  inches.  Jet  of  No. 

1  has  3,  each  of  the  other  two  2J  inches,  diameter. 

Elevator  No.  1  was  lifting  to  a  vertical  height  of  37  feet.     No. 

2  to  28  feet ;  and  No.  3  to  25  feet. 

Of  the  directors,  monitors  or  nozzles,  which  break  down  the  face 
before  its  removal  by  the  elevators,  each  has  a  2J  inch  nozzle  and 
is  connected  bv  a  7-inch  pipe  to  an  11-inch  supply-pipe  which 
in  turn  joins  to  the  18-inch  main.  There  are  16  chains  of  18-inch 
pipe  and  then  48  chains  of  22-inch  pipe,  which  bring  the  water 
from  the  penstock.*  This  last  is  14  by  10  by  12  feet  and  is  connected 
in  turn  with  a  flume  2J  miles  long,  leading  to  the  supply-dams. 
The  flumes,  built  of  Kauri  pine,  is  3  feet  deep  and  3  feet  wide,  hav- 
ing a  gradient  of  9  inches  to  the  chain. 

The  head  of  water  available  at  the  claim  is  600  feet  and  22 
sluice-heads  were  in  use  at  the  time  of  my  visit  out  of  the  total  of 
75  heads,  said  to  be  the  largest  water-right  in  New  Zealand,  and  the 
equivalent  of  3750  cubic  feet  per  minute. 

At  the  present  time,  as  already  stated,  the  pay-gravel  is  confined 
to  3  feet  only;  and  to  remove  the  barren  over-burden,  the  elevators 
have  10-inch  liners,  18-inch  uptake-pipes  and  3-inch  jets.  This,  the 
"  stripping  elevator,"  is  shown  in  position  in  Fig.  l.f  The  side  and 
back-views  (Figs  2  and  3)  explain  themselves.  The  face  of  wash 
is  broken  by  3-inch  nozzles.  This  plant  is  removing  590  tons  per 
elevator  per  8-hour  shift.  Three  men  per  shift  per  elevator  are  em- 
ployed, the  wages  for  the  three  amount  to  22s. — so  that  the  actual 
handling  of  the  gravel  costs  less  than  one-half  penny  or  1  cent  per 
ton.  On  reaching  the  "  pay  dirt "  a  smaller  elevator  is  used,  having 
a  2-inch  jet,  8-inch  liner  and  15-inch  uptake  pipe.  By  this  form  of 
machine  the  gold-bearing  material  is  more  quietly  and  carefully 
handled  than  the  over-burden  of  barren  gravel. 

At  the  present  time  45  sluice-heads  are  in  use,  so  that  each  eleva- 

*  Called  in  California  the  "  bulk-head  "  or  «  pressure-box." 
f  These  drawings  I  owe  to  the  courtesy  of  Mr.  Rene*  Proust,  a  member  of  this 
Institute,  and  engineer  of  the  company. 

2 


18  ALLUVIAL    MINING   IN    OTAGO. 

tor,  with  its  driving-nozzle,  uses  about  15  cubic  feet  per  second, 
under  a  pressure  of  250  pounds  per  square  inch. 

The  sluice-boxes  3  feet  wide,  18  inches  deep  and  12  feet  long,  are 
supplied  with  ordinary  angle-iron  riffles.  The  grade  is  6  inches  per 
12  feet  for  elevator  No.  1,  8J  inches  for  No.  2,  where  the  gravel  is 
notably  coarser,  and  7  inches  for  No.  3.  6  inches  is  found  to  be 
best  adapted  for  the  general  run  of  the  material  treated. 

It  is  intended  to  erect  "  side-runs,"  the  tables  to  be  20  feet  broad 
and  supplied  with  wells  or  traps  to  hold  mercury.  The  manager  is 
fully  alive  to  the  difficulty  of  arresting  the  extremely  fine,  flaky  gold 
by  purely  mechanical  means.  The  gold  occurs  here,  as  at  the  Island 
Block,  in  fine  flakes  mixed  with  black  iron-sand.  On  cleaning  up, 
a  great  deal  of  lead  in  the  form  of  shot  is  found.* 

At  this  mine  the  hydraulic  elevator  has  been  adapted  to  various 
uses  in  a  very  ingenious  manner.  A  common  difficulty  in  placing 
an  elevator  in  position  is  that  the  sinking  of  a  hole  to  receive  the 
foot  of  the  elevator  is  attended  with  delay  and  trouble  owing  to  the 
running  in  of  wash  and  water.  This  has  been  overcome  by  design- 
ing a  special  form  known  as  the  "sinker,"  and  shown  in  Fig.  16, 
where  it  will  be  seen  that  the  intake-pipe  has  a  swivel-joint  which 
enables  it  to  be  readily  accommodated  to  an  uneven  bed-rock.  With 
this  machine  a  place  may  be  rapidly  prepared  for  the  erection  of  a 
larger  elevator. 

At  the  Waipori  Deep  Lead,  at  Waipori,  an  old  bed  of  the  Lam- 
merlaw  Creek  is  worked.  The  gravel  deposit  is  54  feet  deep  and 
from  25  to  30  feet  wide.  It  was  first  worked  by  means  of  a  "  Cali- 
fornia pump  "  and  later  by  means  of  a  steam-winch.  Ten  thousand 
tons  of  gravel  yielded  79  ounces  of  gold,  worth  £295,  and  this  test 
was  considered  sufficiently  satisfactory  to  warrant  the  erection  of  an 
elevator-plant.  The  water  comes  under  a  head  of  390  feet  and  the 
proprietors  have  the  right  to  27  sluice-heads.  The  ditch,  5  feet  by 
2  feet,  is  constructed  to  carry  18  heads  and  has  a  gradient  of  8  feet 
per  mile,  being  constructed  at  a  cost  of  25  shillings  per  chain  or 
£100  per  mile.  The  ground  is  soft,  being  composed  of  a  dense, 
peaty  sod  which  is  readily  cut. 

Where  fluming  is  necessary,  it  has  been  built  of  1-inch  Ribo  or  red 
pine,  and  3  by  2  feet  in  size.  The  fluming,  not  including  trestles, 
costs  Is.  3d.  per  foot.  From  the  penstock  there  are  6100  feet  of 
piping,  of  which  2000  is  18-inch  pipe  (No.  14  gauge),  and  the 

*  This  lead  has  been  expended  upon  the  curse  of  the  country — the  rabbit. 


ALLUVIAL   MINING   IN   OTAGO. 


19 


remaining  4000  feet,  15-inch  pipe  (No.  12  gauge).  The  pipes  are 
double-riveted  and  provided  with  the  usual  air-valves  at  top  of 
bends,  mud-cocks  in  hollows  and  expansion- valves  along  straight 
courses. 

The  supply-pipe  leading  from  the  main  is  11  inches  in  diameter, 
reduced  to  9  before  delivering  the  water  at  the  jet  of  the  elevator. 
This  last  differs  from  the  ordinary  type  in  being  fitted  with  Robert- 
son's patent  atmospheric  jet  (see  Fig.  5).  The  dimensions  are: 
hopper,  16  inches;  throat,  6  inches,  with  a  2|-inch  nozzle  and  a  12- 


Fig.  16. 
PORTABLE  RAPID  SINKER 

FOR 
HYDRAULIC  ELEVATOR 


inch  uptake-pipe.  The  director,  which  breaks  down  the  face  of  the 
gravel,  is  supplied  by  a  7-inch  pipe.  The  brasses  are  2  and  1  j 
inches  respectively. 

The  material  is  delivered  into  sluice-boxes  of  the  ordinary  type — 
12  feet  long,  3  feet  wide,  and  1  foot  deep.  The  sides  of  the  head 
or  delivery -box  are  raised  to  2  feet  6  inches.  The  first  box  receives 
1  inch ;  the  second,  3  inches ;  the  third,  5  inches ;  the  fourth,  6  J 
inches  of  fall  per  12  feet.  The  rush  of  water  keeps  the  first  box 
clear.  The  average  grade  of  the  remaining  boxes  is  6J  inches. 


20  ALLUVIAL    MINING   IN   OTAGO. 

Ordinary  Venetian  or  "angle-iron  on  angle-iron  "  riffles  are  in  use, 
and  under  them  is  placed  common  sacking.  The  end-boxes,  and 
the  first  also,  are  supplied  with  perforated  iron  plate.  The  last  two 
are  lined  with  blanketing.  Of  the  total  gold  obtained,  2  per  cent, 
only  is  found  below  the  first  box. 

At  present,  the  uptake-pipe  being  87  feet  long,  the  vertical  height 
lifted  is  56  feet  from  the  hopper,  or  58  feet  from  the  bed-rock.  By 
utilizing  the  suction*  another  10  feet  will  be  available,  making  66 
feet  in  all.  This  lift  is,  in  proportion  to  the  power  available,  unusu- 
ally high,  but  it  has  in  no  way  tested  the  "aero-hydraulic"  ele- 
vator, which  is  constructed  to  work  under  water  and  not  under  the 
conditions  which  obtain  here.  At  the  Golden  Point  mine,  five  miles 
away,  I  had  an  opportuity  of  noting  the  assistance  which  the  addi- 
tion of  the  "  atmospheric  jet  "  gave  to  the  ordinary  elevator.  There 
the  head  of  water  available  is  103  feet,  supplied  through  an  11-inch 
pipe.  The  water-jet  is  2f  inches  in  diameter,  while  the  uptake-pipe 
is  9  inches.  With  this  force  the  ordinary  rough  wash  was  lifted  to 
32  feet,  the  work  of  breaking  a  12-foot  face  being  done  by  a  2J-inch 
nozzle.  Under  ordinary  conditions,  the  common  elevator  would  not 
lift  higher  than  10  to  15  feet  with  a  head  of  103  feet. 

The  atmospheric  nozzle  or  jet  is  an  improvement  on  the  simple 
elevator;  since  it  acts  on  the  principle  that  by  lightening  the  load 
you  increase  the  effectiveness  of  the  column  of  water.f  In  working 
elevators  a  waste  of  power  is  caused  by  what  is  known  as  "  flood- 
ing;" that  is  to  say,  the  water  from  the  face,  running  into  the  basin 
in  which  the  elevator  stands,  accumulates  there  upon  the  least  stop- 

*  By  adding  a  length  of  pipe  to  the  hopper  of  the  elevator. 

f  The  results  of  the  following  experimental  tests  were  given  to  me  by  the  in- 
ventor : 

No.  1.  2£  gallons  of  water  were  pumped  in  20  seconds  with  air. 

No.  2.  2£  gallons  of  water  were  pumped  in  32  seconds  without  air. 

Pressure  in  the  above  experiments  35  pounds  per  square  inch. 

No.  3.  2£  gallons  were  pumped  in  2  minutes  with  air.  A  trial  was  made  with- 
out air  with  the  same  quantity  of  water  and  no  work  was  done.  Pressure,  8  pounds 
to  the  square  inch. 

No.  4.  10  gallons  were  pumped  with  air  in  1  minute,  30  seconds. 

No.  5.  10  gallons  were  pumped  without  air  in  2  minutes,  10  seconds. 

In  this  test  5|  gallons  were  required  to  pump  the  10  gallons  with  the  air,  and  in 
pumping  without  air  it  took  10  gallons  to  do  the  same  work.  Pressure,  38  pounds 
per  square  inch.  Sand,  shot,  spelter,  etc.,  were  lifted  in  the  proportion  of  half  solid 
matter  to  half  water. 

It  was  found  that  the  machine  emptied  a  given  quantity  of  water  with  air  faster 
than  without  air  in  the  ratio  of  1  to  1.33. 


ALLUVIAL   MINING    IN   OTAGO.  21 

page,*  and  the  hopper  being  soon  under  water  the  air  is  entirely 
shut  off.  Similarly,  when  the  hopper  is  intermittently  under  water, 
the  unequal  irregular  suction  produces  a  fusilading  of  the  piping 
by  the  pebbles,  which  is  productive  of  great  wear  and  tear.  It  is 
found  that  the  admission  of  a  little  air,  by  keeping  the  hopper 
partly  open,  cannot  be  controlled,  though  it  is  desirable  in  that, 
while  increasing  the  wear  on  the  liner,  it  adds  to  the  effectiveness 
of  the  machine.  To  avoid  those  difficulties  and  to  obtain  these 
advantages,  there  is  introduced  a  constant  air-supply  by  means  of 
the  addition  shown  in  Fig.  5.  An  annular  air-current  passes  from 
the  outer  air  through  a  jet  supplied  by  a  pipe  which  extends  above 
the  water-line.  This  forms  an  air  cushion  round  the  water-jet  and, 
by  preventing  it  from  feathering  or  breaking,  tends  to  maintain  a 
uniform  velocity.  The  diminution  of  the  suction  is  not  sufficient  to 
affect  injuriously  the  feeding,  while  the  lightening  of  the  column 
aids  the  effectiveness  of  the  machine.  There  is  also  a  decrease  in 
wear  and  tear,  since  the  admission  of  a  constant  air-supply  secures  a 
constant  speed  to  the  ascending  column  of  gravel  and  water. 

Before  leaving  this  part  of  the  subject,  a  few  general  conclusions 
may  be  in  place.  The  alluvial  deposits  df  Otago  are  of  remarkable 
extent,  more  particularly  the  lake-  and  river-beds  along  the  course 
of  the  Clutha,  Shotover  and  Kawarau  rivers.  These  latter  were  not 
to  any  large  extent  accessible  for  mining  previous  to  the  introduc- 
tion of  the  elevator,  because  the  frequent  rapid  rise  of  the  rivers  pre- 
vents the  satisfactory  use  of  the  dredge,  and  ordinary  sluicing  is 
rarely  possible  owing  to  the  want  of  "dump. "  The  most  extensive 
deposits  are  in  the  flats  formed  from  old  lake-basins ;  but  their  level 
is  such  that  the  seepage  from  the  river  rapidly  floods  the  miner's 
claim.  To  overcome  the  difficulty  by  ordinary  pumping  was  not 
economically  practicable.  The  hydraulic  elevator,  however,  renders 
these  deposits  available  for  exploitation,  and  its  introduction  is  rap- 
idly spreading ;  the  expense  of  the  first  installation  of  the  costly 
plant  required  being  met  by  the  consolidation  of  small  claims  under 
companies  provided  with  the  necessary  working-capital. 

The  elevator  will  have  a  great  future  in  Otago;  but,  in  the  haste 
to  use  a  new  machine,  there  is  a  tendency  to  discard  the  assistance 
of  methods  which  have  previously  rendered  good  service.  Ground- 
sluicing  has  been  put  aside,  and  there  is  a  tendency  to  make  the  ele- 
vator do  work  which  can  sometimes  be  less  expensively  done  by 

*  As  when  a  large  stone  sticks  in  the  throat  of  the  elevator. 


22  ALLUVIAL   MINING   IN  OTA  GO. 

simpler  means.*  In  the  blocking  out  of  ground  there  is  room  for 
improvement.  It  is  not  very  difficult  to  erect  a  good  plant,  and  it 
is  easy  to  commence  the  attack  on  a  face  of  gravel,  but  the  syste- 
matic blocking  out  of  the  claim  tries  the  resources  of  those  whose 
experience  has  been  mainly  confined  to  other  forms  of  mining. 

DREDGING. 

The  first  gold-seekers  who  prospected  the  sands  of  the  Shotover 
and  Molyneux  rivers  restricted  their  search  to  the  easily  accessible 
deposits  which  had  accumulated  under  the  shelter  of  rocky  bars ;  and 
when  the  auriferous  sands  were  found  to  extend  under  the  waters  of 
the  river,  they  turned  the  stream  by  means  of  wing-dams.  The  rich 
alluvium  was  found,  however,  in  places  where  this  mode  of  opera- 
tion was  impracticable  or  too  costly,  and  in  such  places,  standing 
shovel  in  hand,  they  snatched  with  difficulty  the  golden  sand,  which 
increased  in  richneas  the  less  accessible  it  became.  The  simple 
shovel  was  useless  in  a  fast  current ;  hence  the  next  step  was  to  con- 
trive a  ladle  or  spoon  with  which  to  scoop  up  the  river-bed.  A  piece 
of  hide  fastened  to  an  iron  rim  was  arranged  behind  the  modified 
blade  of  a  shovel,  and  this  at  the  end  of  a  long  pole  helped  to  in- 
crease still  further  the  area  available  for  work.  Soon,  however,  the 
distance  from  the  shore,  and  with  it  the  increasing  depth  of  water, 
prevented  further  advance.  A  barge  or  punt  was  then  built,  the 
pole  was  lengthened  to  20  feet  or  more,  the  scoop  was  enlarged  so  as 
to  hold  a  barrowful,  and,  the  increased  weight  requiring  other  than 
mere  hand-labor,  a  winch  and  tackle  were  rigged  up.  This  now 
became  the  "spoon-dredge,"  the  forerunner  of  the  numerous  types 
of  bucket-dredges  which  have  started  a  new  branch  of  the  mining 
industry  of  New  Zealand. 

The  spoon-dredge  served  its  purpose,  but  the  numerous  mines 
along  the  banks  of  the  river  had  begun  to  send  down  tailings,  which 
soon  covered  the  bottom  with  a  rapidly  increasing  thickness  of 
valueless  material.  The  spoon-dredge  was  not  capable  of  coping 
with  this  fresh  difficulty,  but  the  rapidly  flowing  river  suggested  the 
greater  power  now  needed  to  replace  human  muscle;  a  water-wheel 
took  the  place  of  the  winch,  and  the  "  current-  wheel  -dredge"  was 
invented.  This  consisted  of  a  simple  form  of  bucket-dredge,  worked 
by  an  under-shot  wheel  placed  at  the  side  of  a  punt.  The  power 
needed  to  propel  the  machine  severely  restricted  its  usefulness,  for  it 

*  By  this  I  refer  particularly  to  the  removal  of  the  barren  overburden,  which 
can  be  done  by  ordinary  ground-sluicing. 


ALLUVIAL,    MINING    IN    OTAGO.  23 

could  not  be  employed  in  the  back-waters,  or  indeed  anywhere  but 
in  the  full  force  of  the  river-current,  and  the  richest  parts  of  the 
channel  had  therefore  to  remain  untouched.  Steam  was  substituted 
for  water-power,  and  the  bucket-and -ladder  type  of  dredge  was  ad- 
vanced a  stage  further  by  the  addition  of  revolving  sizing-screens, 
winches  for  mooring  and  pumps  for  raising  the  water  required  to 
separate  the  fine  gold-bearing  silt  from  the  coarse  gravel.  This 
brings  us  down  to  to-day,  when  the  river-sands  and  the  sea-beaches 
of  the  South  Island  are  worked  by  a  force  of  over  50  dredges,  pro- 
pelled by  water,  steam  and  electricity. 

When  I  was.  at  Duuedin,  in  1890,  it  was  difficult  to  find  a  man 
who  had  not  located  some  acres  of  land  on  river-bank  or  sea-shore. 
Dredging  properties  were  plentiful  as  "  leaves  in  Vallombrosa 7'  and 
"  the  potentialities  of  acquiring  wealth  beyond  the  dreams  of  ava- 
rice" were  offered  on  every  hand.  Returning  in  March,  1891,  I 
found  that  the  number  of  dredges  at  work  had  largely  increased, 
with  a  corresponding  diminution  in  the  dredging  fever.  The  results 
had  been  disappointing. 

The  success  of  the  Dunedin  dredge  was  the  main  cause  of  the 
dredging  fever.  Directed  by  a  man  of  great  experience  in  this 
branch  of  engineering,  and  put  to  work  in  a  part  of  the  river 
Clutha  which  soon  proved  very  rich,  this  dredge  returned  in  ten 
months  two-thirds  of  the  paid-up  capital  of  the  company  which 
owned  it.  One  of  the  Shotover  dredges  had  also  been  fairly  suc- 
cessful, while  on  the  sea-beach  the  Wai  papa  dredge,  exploiting  the 
titaniferous  gold-bearing  sand,  had  made,  under  many  difficulties, 
very  encouraging  returns.  It  was  at  once  found  that  the  extent  of 
ground  available  for  this  mode  of  working  was  almost  unlimited  ; 
the  river-channels  and  the  sea-coast  were  soon  covered  with  loca- 
tions; claims  were  taken  up  and  floated  into  companies,  the  vendor 
receiving,  for  ground  which  had  cost  him  but  a  few  shillings,  a  large 
sleeping  interest  in  a  concern  to  the  working  capital  of  which  he 
contributed  nothing.  Large  areas  were  assumed  to  be  valuable  on 
account  of  reported  rich  yields  obtained  by  the  diggers  from  spots 
representing  a  very  small  proportion  only  of  the  total  field  to  be 
worked.  No  tests,  or  only  unsystematic  tests,  were  made.  It  was 
overlooked  that  the  rapid  rise  of  the  river  would  prevent  work 
during  many  months  in  the  year.  Moreover,  in  this  form  of  mining 
the  experience  so  far  accumulated  had  been  but  small,  and  the  saving 
of  the  gold  was  often  attempted  under  conditions  which  were  hope- 
less. Gradually  the  enterprising  investor  awoke  to  the  stern  fact 


ALLUVIAL    MINING    IN   OTAGO.  25 

that,  like  all  other  branches  of  mining,  dredging  required  judgment, 
care  and  experience. 

I  will  here  describe  two  representative  bucket-dredges.  Figs.  17 
and  18*  show  the  general  mode  of  construction.  The  pontoon  in 
this  case  has  a  length  of  80  feet,  a  width  of  18 J  feet,  and  a  depth 
of  4J  feet.  The  ladder  is  constructed  to  work  to  a  depth  of  20 
feet  below  the  surface  of  the  water.  The  power  to  propel  the 
machinery  is  derived  from  the  river,  and  is  transmitted  as  elec- 
tricity. 

The  Dunedin  dredge  is  working  the  bottom  of  the  Clutha  at  a  point 
ab9ut  3  miles  above  the  town  of  Roxburgh.  The  deposit  covering 
the  rocky  bed  of  the  river  consists  here  of  20  to  25  feet  of  barren 
drift,  overlying  a  thickness  of  2*  to  2J  feet  of  gold-bearing  wash. 
Sometimes  the  "  pay  "  thins  to  6  inches.  The  overburden  of  drift 
consists  of  small-sized  gravel,  but  the  pay- wash  is  composed  of  large 
boulders,  among  the  interstices  of  which  occurs  the  gold.  Black 
sand  is  found  in  both  drift  and  pay-wash,  that  of  the  drift  originat- 
ing, together  with  the  bulk  of  the  material  in  which  it  occurs,  from 
the  mines  along  the  river.  The  gold  is  similar  to  that  obtained  else- 
where along  the  Clutha,  consisting  of  fine,  flat  flakes  in  a  black  iron- 
sand.  Gold  is  not  seen  in  the  quartz  of  the  pebbles. 

This  dredge  has  a  double  ladder  of  buckets  holding  2  cubic  feet 
each,  12  emptying  per  minute  on  each  side,  giving  the  machine  a 
capacity  of  106  cubic  yards  per  hour.  There  are  31  buckets  on  each 
side,  the  material  from  which  passes  through  the  two  perforated 
iron  cylinders,  the  larger  pebbles  being  ejected  along  an  iron  shoot 
which  returns  them  to  the  river,  while  the  fine  gravel  passes  over  a 
table  8  feet  long  by  7J  feet  wide.  The  grade  is  2  inches  per  foot, 
and  cocoanut  matting  is  used  to  arrest  the  gold.  This  table  and  the 
similar  one  on  the  other  side  discharge  upon  a  middle  table,  8  feet 
long  by  4  feet  wide,  which  is  provided  with  iron-bar  riffles.  From 
here  the  gravel  falls  into  the  river.  The  above  comprises  the  whole 
apparatus  employed  in  the  saving  of  the  gold.  The  cocoanut  mat- 
ting is  washed  at  regular  intervals  in  a  tank,  the  gold  being  subse- 
quently separated  from  the  black  sand  by  panning. 

The  motive  power  for  the  machinery  is  derived  from  steam,  the 
fuel  used  being  the  lignite  which  occurs  at  Coal  Creek,  3  miles  up 
the  river.  The  price  is  8  shillings  per  ton,  delivered  at  the  bank, 

*  The  drawing  I  owe  to  the  courtesy  of  Mr.  Kobert  Hay,  C.E.,  of  Dunedin,  who 
has  designed  many  of  the  best  dredges  in  use  in  Otago. 


26  ALLUVIAL   MINING   IN   OTAGO. 

whence  it  is  ferried  by  boat.  The  daily  consumption  is  3  tons. 
Electric  light  enables  work  to  be  uninterrupted. 

The  dredge  had  just  re-started  at  the  time  of  my  visit,  after  a 
stoppage  due  to  the  rise  in  the  river,  which  was  even  then  flowing  9 
knots  per  hour.  During  flood-time  the  rate  of  flow  reaches  12  knots, 
while  the  average  is  7  knots  per  hour.  The  working  expenses  are 
£250  per  month,  This  includes  the  wages  (£160)  of  9  men  and  a 
dredge-master.  The  coal  bill  is  £30.  The  balance  of  the  £250  is 
taken  up  by  repairs  and  supplies.  The  average  of  steady  work  is 
only  4  days  per  week  of  6  working  days.  This  does  not  allow  for 
the  interruption,  often  for  weeks,  due  to  floods.  From  December, 
1889,  to  October,  1890,  dividends  amounting  to  £4080  were  paid  on 
a  nominal  capital  of  £7200,  and  a 'paid-up  capital  of  £6240.  After 
October,  work  ceased  on  account  of  the  spring  floods  until  the  first 
week  in  December.  The  directors'  report  for  the  6  months  ending 
July  2,  1890,  states  that  the  gold  obtained  amounted  to  884  ounces, 
5  pennyweights,  8  grains, — value  £3316 — out  of  which  £1680  was 
returned  in  dividends. 

The  Dunedin  dredge  is  working  the  auriferous  gravel  lying  upon 
the  rock-bed  of  the  swift-flowing  Clutha  ;  but  the  Waipori  dredge, 
which  we  will  next  consider,  is  placed  under  much  more  favorable 
conditions.  The  Waipori  river  is  a  small  stream,  running  through 
a  flat  valley  surrounded  by  rolling  foot-hills.  A  wide  deposit  lies 
in  the  hollow  of  the  valley,  and  above  it  flows  the  present  stream. 
The  gold  obtained  does  not  lie  upon  the  bed-rock  of  the  original 
channel,  which  is  much  deeper,  but  at  a  horizon  marked  by  coarse 
sand — the  (t  false  bottom"  of  the  miners. 

The  dredge  is  of  the  bucket-and-ladder  type.  The  stream  is  cf 
insufficient  depth  to  float  it ;  but  the  dredge  makes  its  own  water- 
way by  the  removal  of  the  gravel.  The  capacity  is  7600  cubic 
yards  per  week  of  125  to  130  working  hours.  The  movement  of 
the  pontoon  is  directed  by  4  winches  operating  wire  ropes  fastened 
to  the  shore.  The  engine  is  of  40  horse-power,  supplying  the  power 
necessary  to  work  the  buckets  themselves,  as  well  as  the  pump  which 
gives  the  water  necessary  for  the  tables.  The  contents  of  each  bucket 
as  it  comes  up  are  emptied  into  a  revolving  sizing-cylinder,  con- 
structed of  horizontal  iron  bars.  The  fine  silt  goes  straight  to  the 
tables,  while  the  coarse  passes  to  another  sizing-cylinder  (this  time 
of  perforated  boiler-plate),  which  separates  the  coarse  gravel  and 
boulJers.  These  fall  into  the  stream  from  an  iron  shoot,  while 
the  line  goes  to  the  tables,  which  are  arranged  on  either  side  and 
are  covered  with  coarse  cocoanut  matting,  with  linen  underneath. 


ALLUVIAL,   MINING   IN   OTAGO.  27 

The  following  figures  will  indicate  the  cost  of  operations  during 
the  period  of  a  year. 

£.       s.    d. 
Repairs  and  Alterations, 222     9     1 

This  was"  chiefly  in  pins  and  bushes.  The  wear  and  tear  is  mostly 
about  the  buckets.  The  lips  last  for  two  years;  and  the  pins  on 
which  the  buckets  are  hinged,  have  an  average  life  of  3  months. 

£.          s.      d. 
Wages,        .        .        . 1192     16    4 

This  includes  the  pay  of  8  men  and  3  boys  per  day.  One  engi- 
neer, one  winch-man  and  one  boy  to  attend  to  the  tables,  on  each 
shift,  making  6  men  and  3  boys  per  24  hours.  Then  there  are  to 
be  added  the  dredge-master  and  a  blacksmith. 

£.       s.    d. 
Material,'     .        .        ;    "'  1  "f V     5.         .        .        .        272     9    5 

This  includes  the  shed  on  the  shore  which  serves  as  an  office,  forge 
and  tool-house. 

£.       s.      d. 

Coal,    .         .        .      •  .        .     '   .....        507     12    0 
Firewood,    .        V      '. '    >;V  ' '''';-       ....        377      6     0 

The  wood  (manuka)  costs  £1  15s.  per  cord.  Coal  (from  West- 
port)  costs  55s.  per  ton,  delivered. 

£.       s.     d. 
Rent,    .       •*        .'      -V  •••:•* 293    0    0 

This  is  the  amount  (at  10s.  per  acre)  paid  to  the  government  as 
rent  for  the  claim. 

During  the  year  the  first  two  months  were  taken  up  by  the  erec- 
tion of  the  plant  and  in  the  remaining  ten  the  gold  obtained 
amounted  in  value  to  £3095,  8s.  6d. 

The  cost  of  the  dredge,  including  fees  to  the  engineer,  was  £3380, 
14s.  3d. 

The  weekly  cost  upon  the  ground  is  £30  for  labor,  £20  for  fuel, 
or  (including  repairs)  about  £65  in  all. 

Three  typical  weekly  records  are  as  follows  : 

First  Week.  Yield  21  ounces,  16  pennyweights.  Time  of  actual 
work  140  hours. 


28  ALLUVIAL   MINING   IN    OTAGO. 

Ground  lifted  8400  yards.  Depth  of  lift  10  feet.  Firewood,  10 
cords. 

Second  Week.  Yield  33  ounces,  13  pennyweights,  18  grains. 
Time  126  hours. 

Ground  lifted,  8400  yards.  Depth  about  13  feet.  Firewood,  10 
cords. 

Third  Week.  Yield  29  ounces,  12  pennyweights.  Time  126 
hours. 

Ground  lifted  7560  yards.  Depth  about  13  feet.  Firewood, 
10}  cords. 

Up  to  that  time  the  dredge  had  handled  very  little  virgin  ground, 
the  material  consisting  chiefly  of  the  tailings  carried  down  from  old 
sluicing-claims.  Since  then  it  has  reached  solid  ground ;  and  the 
results,  with  the  same  expense,  have  reached  50  ounces  per  week. 

This  dredge  is  working  under  conditions  admirably  suited  to  its 
capabilities.  The  working-cost  is  slight,  the  amount  of  capital  tied 
up  is  very  small,  the  area  of  the  claim  is  large  and  the  danger  of 
floods  nil.  The  depth  at  which  it  is  working  varies  from  10  to  15 
feet.  The  "  false  bottom7'  of  compact  coarse  sand  enables  the  buckets 
to  get  well  under  the  pay-wash,  and  avoids  a  great  deal  of  the  wear 
and  tear  incident  to  working  upon  a  rocky  bed. 

The  material  treated,  while  it  is  very  similar  to  that  of  the  mines 
on  the  Clutha,  yet  contains  gold  more  shotty  than  that  of  the  big 
river-claims.  The  gold  of  the  Waipori  flats  came  in  large  measure 
from  the  erosion  of  the  neighboring  quartz-lodes — the  O.  P.  Q.  and 
other  reefs.  While  on  the  dredge  I  was  shown  a  round,  white  quartz 
pebble,  taken  that  morning  from  one  of  the  buckets,  which  was  of 
the  size  of  a  hand,  and  showed  several  splashes  of  gold  as  large  as 
a  small-finger  nail.  Such  a  find,  very  unusual  in  the  alluvial  mines 
of  Otago,  marks  the  somewhat  exceptional  conditions  under  which 
this  deposit  was  probably  formed. 

GOLD-SAVING. 

The  methods  used  are  of  the  crudest  kind.  There  is  no  doubt 
that  the  river  receives  back  more  than  half  of  the  gold  contained  in 
the  material  raised  by  the  dredge.  The  tables  at  Waipori  are  some- 
what larger  than  those  of  the  Dunedin  dredge;  but  in  both  casesit 
appears  the  height  of  absurdity  to  think  that  they  can  save  a  large 
percentage  of  the  fine,  flaky  gold  carried  along  in  such  a  large  flow 
of  water  and  amid  so  great  a  volume  of  sand  and  gravel.  The 
report  of  the  Directors  of  the  Dunedin  dredge  company  says  that 


ALLUVIAL   MINING   IN   OTAGO.  29 

"  the  dredge-master  reports  that  the  gold-saving  appliances  are  all 
that  could  be  desired."  This  is  the  severest  satire  upon  the  childish 
efforts  made  to  save  the  gold,  fully  sixty  per  cent,  of  which  must 
be  a  mere  passenger  through  the  apparatus  designed  to  arrest 
it.  Over  a  hundred  cubic  yards  of  gravel,  together  with  the  water 
employed  to  transport  it,  are  in  this  case  handled  by  the  dredge 
every  hour,  and  of  this  a  very  large  proportion  passes  over  the  sur- 
face of  two  tables  covered  with  cocoanut  matting  whose  dimensions 
are  8  feet  by  7J  feet.  There  is  no  opportunity  whatever  given  for 
a  separation  of  the  gold  from  the  mass  of  heavy  black  iron-sand 
and  the  sediment  in  which  it  is  enveloped.  The  surface  over  which 
it  passes  is  far  too  small,  and  the  distance  over  which  it  travels  is 
altogether  too  short  to  enable  it  to  be  arrested  by  the  simple  means 
adopted.  What  is  collected  is  in  spite,  rather  than  by  reason,  of 
the  efforts  made  to  catch  it,  and  represents  a  small  proportion  only  of 
the  gold  in  the  material,  the  larger  part  being  lifted  from  the  river 
only  to  be  returned. 

THE  USE  OF  MERCURY. 

The  use  of  mercury  is  not  familiar  to  the  alluvial  miner  of  Otago, 
as  it  is  to  his  brethren  elsewhere.  There  exists  a  curious  idea  that 
it  will  not  act  in  cold  weather,  due  no  doubt  to  the  fact  that  the 
cleaning  up  in  the  mills  and  mines  is  invariably  done  with  hot  water. 
Of  course  there  is  a  substratum  of  truth  in  this  idea,  since  amalga- 
mation is  as  a  rule*  retarded  by  cold  and  assisted  by  heat,  but  within 
narrow  limits  only  and  not  to  such  an  extent  as  to  make  the  fact  of 
any  great  practical  importance.  It  certainly  will  not  explain  why 
the  Otago  digger  has  "  left  in  the  cold  "  one  of  the  best  friends  of 
mining  all  the  world  over.  From  an  examination  of  the  conditions 
under  which  the  gold  of  the  alluvium  of  Otago  occurs,  particularly 
in  the  deposits  of  the  Clutha  and  its  tributaries,  I  am  strongly  of  the 
opinion  that  the  use  of  mercury  will  have  to  be  resorted  to  if  any 
large  percentage  of  the  precious  metal  is  to  be  extracted. 

In  the  case  of  the  elevator-plant  the  example  of  California  can  be 
followed  and  mercury  placed  in  the  riffles  of  the  sluice-boxes  them- 
selves. Then  it  requires  but  an  extension  of  the  idea  of  side-runs, 

*  In  the  mountains  of  Colorado,  at  an  altitude  of  8500  feet,  the  amalgamation  at 
the  stamp-mills  meets  with  no  obstacle  in  winter.  On  the  contrary,  it  is  curious  to 
note  that  the  mill-men  of  Gilpin  county  unite  in  asserting  that  the  cold  weather  is 
beneficial  to  amalgamation,  for  the  reason  that  warmth  thins  the  mercury  and  causes 
it  (with  the  vibration  due  to  the  falling  stamps)  to  run  off  the  plates. 


30  ALLUVIAL,   MINING   IN   OTAGO. 

preceded  by  under-currents,  to  permit  the  further  use  of  the  quicksil- 
ver in  wells  or  traps.  With  the  dredges  the  first  alteration  of  existing 
methods  which  is  demanded  is  the  enlargement  of  the  area  over 
which  the  material  passes.  Dredges  are  now  constructed  at  Dune- 
din  to  handle  over  150  tons  per  hour.  This  requires  a  very  large 
surface  to  effect  even  the  roughest  separation  of  the  fine  gold-hearing 
silt  from  the  large  mass  of  non-auriferous  wash.  The  Wei  man 
dredge  at  Waipapa*  which  is  supplied  with  tables  24  feet  by  30  feet, 
having  an  incline  of  }-inch  per  foot,  is  designed  on  common-sense 
principles  and  supplies  an  example  to  the  other  dredges  of  Otago. 
But  even  the  dispersion  of  the  material  over  such  an  enlarged  sur- 
face will  not  suffice  to  collect  the  finer  particles  of  gold.  Mechani- 
cal means  must  be  assisted  by  chemical ;  gravitation  must  be  fol- 
lowed by  amalgamation. 

The  fineness  of  the  gold  in  the  New  Zealand  alluvium  may  be 
imagined  when  it  is  stated  that  by  actual  count  it  requires  six  to 
seven  thousand  particles  of  the  gold  as  found  on  the  west  coastf  to 
form  a  grain  in  weight.  It  will  be  said  that,  as  a  matter  of  practice, 
it  has  been  noted  that  very  little  gold  finds  its  way  beyond  the  first 
strips  of  matting  and  that  on  washing,  the  bottom  strips  are  seen  to 
collect  scarce  any.J  This  is  after  the  fashion  of  the  millman  who 
carefully  assays  his  tailings  but  fails  to  note  how  much  gold  he  is 
losing  in  the  slimes  which  are  carried  down  stream  to  cheer  the 
the  hearts  of  a  tribe  of  Mongolians.  The  evidence  obtained  by  such 
tests  is  an  ignis  fatuus  to  the  miner,  deluding  him  into  a  blissful  ig- 
norance of  his  losses.  The  fact  is  that  in  such  cases  the  gold  lost 
is  in  an  entirely  different  condition  from  that  saved,  and  methods 

f  This  dredge  was  idle  during  the  time  of  ray  stay  in  Otago,  owing  to  a  change 
which  was  being  made  in  its  construction.  An  interesting  description  appeared  in 
the  records  of  the  Mining  Conference  held  at  Dunedin  in  1890,  written  by  Mr.  Jas. 
Allen,  a  member  of  this  Institute.  This  dredge  is  working  the  sea-beach,  those 
portions  where  the  titaniferous  gold-bearing  sand  has  been  concentrated  by  the 
action  of  the  prevailing  winds. 

J  Best  known  by  the  Hokitika  discoveries. 

$  The  following  experiments  were  made  at  Waipapa: 

First  Experiment. — The  bottom  cloths— those  16  to  18  feet  from  the  head — were 
washed  separately  from  the  remainder,  with  the  result :  Amalgam  for  eight  days- 
top  cloths,  89  ounces  16  pennyweights;  bottom  cloths,  4  pennyweights  5  grains. 

Second  Experiment. — The  second  row  of  cloths  from  the  bottom,  that  is  from  14  to 
16  feet  were  separately  washed.  The  amalgam  from  the  top  cloths  was  90  ounces ; 
the  cloths  from  14  to  16  feet  yielded  8  pennyweights. 

It  is  necessary  to  add  here  that  the  produce  becomes  amalgam  only  in  cleaning 
up,  mercury  being  used  simply  in  collecting  the  residues  from  the  washing  of  the 
plush— which  last  does  the  direct  gold-saving. 


ALLUVIAL,   MINING   IN    OTAGO.  31 

which  serve  to  arrest  the  latter  are  entirely  insufficient  to  hold  the 
former. 

The  character  of  the  gold  is  in  no  way  prejudicial  to  amalgama- 
tion. In  both  river-banks  and  sea-beaches,  it  is  bright,  of  high  carat- 
age,  and  not  "  rusty,"  or  mixed  with  minerals  inimical  to  mercury. 
On  the  other  hand  its  fine  flakey  character  makes  it  particularly  hard 
to  arrest  by  purely  mechanical  methods.  The  thin  plates  of  gold, 
especially  when  their  edges  are  turned,  as  must  often  happen  during 
the  treatment  the  gravel  undergoes,  are  especially  adapted  to  be 
transported  by  water. 

The  material  used  for  the  gold-saving  is  cocoanut  matting,  which 
withjn  certain  limits  answers  admirably.  Owing  to  its  porous  char- 
acter, it  is  usually  supplemented  by  linen  placed  along  the  wood- 
work of  the  tables  or  sluice-boxes.  Some  of  the  dredges  employ 
plush.  The  choice  is  largely  a  matter  of  expense.  At  the  Island 
Block  it  was  found  that  the  plush  used  in  the  side-runs  caught  too 
much  of  the  black  iron-sand  and  got  quickly  choked.  At  Waipapa, 
with  a  very  large  proportion  of  fine  black  sand,  it  answered  well. 
The  difference  of  experience  is  due  probably  to  the  quantity  of  water 
used,  and  the  gradient  over  which  the  material  passed. 

The  dredge  has  added  largely  to  the  area  available  fQr  mining 
operations.  In  this  branch  of  mining,  Otago  is  opening  up  a  new 
and  important  field.  The  practical  result  of  the  experience  so  far 
obtained  proves  that  the  bucket-dredge,  though  admirably  simple 
and  inexpensive,  is  best  suited  to  the  raising  of  auriferous  alluvium 
ying  upon  a  "  false  bottom."  Upon  a  true  bed-rock  the  wear  is 
much  increased,  and  the  effectiveness  much  diminished.  Everyone 
knows  how  difficult  it  is  to  scoop  fine  gold  mixed  with  gravel  under 
water  by  the  aid  of  a  shovel.  It  runs  off.  The  bucket  of  the  dredge 
is  a  modified  shovel.  For  irregular  bottoms,  the  suction-pump 
dredge,  of  which  the  Welman  is  a  good  example,  will  be  found  best 
adapted.  In  this  case  a  powerful  centrifugal  pump  draws  up  the 
water,  gravel  and  gold,  delivering  them  to  the  le.vel  of  the  tables. 
At  Waipapa,  stones  35  to  40  pounds  in  weight  have  been  sent  up  by 
the  pump;  and  it  only  requires  an  improvement  in  construction, 
giving  durability  and  strength,  to  render  it  a  most  effective  machine 
for  this  class  of  work.  A  dredge  thus  provided  is  able  to.  sweep  the 
bottom  clean.  After  that,  the  extraction  of  the  gold  becomes  the 
great  question ;  and  in  this  direction,  as  we  have  seen,  there  is  a  wide 
margin  for  improvement. 

Time,  however,  will  remedy  these  defects,  and  the  Otago  miner 


32  ALLUVIAL   MINING    IN    OTAGO. 

may  meanwhile  point  with  pride  to  the  fact  that  he  has  shown  the 
possibility  of  working  the  sands  of  the  sea-shore  at  a  profit,  when 
they  contain  but  two  grains  of  gold  per  ton. 

This  concludes  my  notes  upon  a  mining-field  but  little  known  on 
this  side  of  the  equator.  The  chief  lesson  it  conveys  is,  that  we 
should  seek  to  profit  by  the  experience  of  others.  Otago  has  much 
to  learn  from  California  in  lode-mining  and  quartz-milling ;  but 
California  would  do  well  to  study  the  steps  of  Otago  in  hydraulic 
elevating  and  dredging.  The  miner  should  be  the  least  conserva- 
tive of  men  ;  his  motto  should  be  "  pass  it  on  ;"  the  same  difficulties 
should  never  require  to  be  overcome  twice;  and  thus  should  iu» 
avoided  that  worst  of  all  wastes,  the  waste  of  experience.  , 

NOTE  BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other  errors, 
or  communications  for  publication  as  "Discussion,"  or  independent 
papers  on  the  same  or  a  related  subiect,  are  earnestly  invited. 


\1 

SUBJECT  TO  BEVISION. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Development  of  Colorado's  Mining  Industry.* 

BY  T.    A.    RICKARD,    STATE  GEOLOGIST,   DENVER,   COLO. 
(Colorado  Meeting,  September,  1896.) 

THE  history  of  this  State  is  that  of  one  generation.  Thirty- 
six  years  only  have  elapsed  since  the  birth  of  that  beneficent 
industry  whose  footsteps  were  the  first  to  traverse  the  wilder- 
ness of  the  prairies  and  penetrate  the  solitude  of  the  moun- 
tains. So  soon  is  history  made.  The  men  who  halted  on  the 
rolling  plain  where  Denver  now  stands  and  gazed  westward  at 
the  snow-clad  ranges  in  eager  questioning  of  their  possibilities 
of  golden  wealth,  have  lived  to  see  a  noble  city  built  where 
once  their  camp-fires  burned,  and  have  participated  in  the 
discovery  of  magnificent  series  of  productive  mines  amid  the 
mountains  which  seemed  at  that  time  the  Ultima  Thule  of  their 
pilgrimage. 

To  those  who  investigate  the  workings  of  our  complicated 
mining  and  metallurgical  industries,  the  story  of  their  evolution 
from  humble  beginnings  will  appear  an  instructive  romance. 
The  record  that  tells  it  presents  features  common  to  the  growth 
of  modern  mining  regions,  but  also  bears  aspects  peculiar  to 
those  local  conditions  upon  which  the  development  of  these  in- 
dustries is  so  essentially  dependent. 

In  the  summer  of  1849  a  party  of  seven  Georgians  were 
taking  a  herd  of  thoroughbred  horses  across  the  continent  to 
California.  They  reached  Camp  Lyon,  on  the  Arkansas,  in  Oc- 
tober, and,  meeting  James  Dempsey,  a  government  guide,  they 
were  persuaded  by  him  that  it  was  too  late  to  cross  the  moun- 
tains that  season.  His  advice  was  followed,  and,  moving  north- 
ward, they  established  a  winter  camp  at  the  junction  of  Cherry 
creek  and  the  Platte.  Upon  a  sand-bar,  lining  the  south  side 
of  the  river,  they  built  two  cabins.  During  the  closing  months 
of  that  year  they  prospected  the  alluvial  banks  of  Cherry  creek, 

*  This  paper  was  subsequently  presented  before  the  Colorado  Scientific  Society. 
The  present  version,  however,  is  later  in  publication,  and  contains  some  additions. 


2     THE  DEVELOPMENT  OF  COLORADO'S  MINING  INDUSTRY. 

but  did  not  penetrate  into  the  mountain  canons  for  fear  of  the 
Indians.  Gold  was  found  in  several  places,  and  particularly  at 
a  point  16  miles  up  the  stream.  From  the  feathers  of  the  wild 
geese  which  they  shot,  they  made  quills,  serving  as  receptacles 
for  small  quantities  of  gold-dust. 

This  party  consisted  of  Dr.  Russell  and  his  brother,  Green 
Russell,  A.  T.  Lloyd,  G.  W.  Kiker,  Charles  Kiker  and  P.  H. 
Clark.  Early  in  1850  they  crossed  the  range  by  the  Bridger 
pass  and  went  on  to  California.  They  mined  near  Downieville 
and  were  successful.  Mention  was  occasionally  made  of  the 
gold  found  in  western  Kansas  when  on  their  way  across  the 
plains.  The  goose-quills  were  evidenced  in  proof  of  the  story. 
In  the  spring  of  185Y  they,  with  others,  sold  out  their  inter- 
ests in  California  and  returned  to  Georgia.  Before  separating 
it  was  agreed  among  several  of  them  that  in  the  near  future 
they  would  form  a  prospecting  party  to  go  to  western  Kansas 
and  search  for  gold. 

In  May,  1858,  eleven  of  them  met  at  the  Planters'  House  in 
St.  Louis.  In  addition  to  the  original  seven  there  were  present 
J.  A.  O'Farrell,  three  men  of  the  name  of  Chastine  and  another 
called  Fields.  All  save  two  were  old  Californians.  Having 
organized,  they  went  to  Leavenworth  by  water  and  thence  to 
Camp  Hariiey  along  the  military  road.  Late  in  July  they  left 
this  frontier  post,  accompanied  by  an  escort  of  twenty  men 
under  the  command  of  Captain  Lyon.  In  August  the  party 
reached  the  log  cabins  on  the  Platte.  The  banks  were  at  that 
time  covered  with  the  wild  cherries  which  gave  the  tributary 
stream  its  name.  As  soon  as  camp  had  been  established,  they 
went  to  the  places  where  Russell  and  his  friends  had  found  gold 
in  1849.  Sufficient  was  found  to  encourage  them.  Prospect- 
ing parties  were  then  organized.  One  of  these  went  northward 
until  they  came  to  a  mountain  stream  full  of  large  boulders. 
They  went  up  to  the  forks  of  Boulder  creek.  In  a  small  basin 
on  the  left  hand  branch  they  found  gold,  and  called  the  spot 
Gold  run.  Another  party  went  across  the  intervening  ridges 
to  Fall  river,  and  over  into  Spring  gulch.  They  did  not  de- 
scend into  the  valley  of  North  Clear  creek  at  that  time,  but 
crossed  Quartz  hill  and  found  rich  gravel  at  Russell  gulch, 
named  after  the  discoverer,  Green  Russell.  It  was  too  near 
winter  to  begin  serious  mining.  They  returned  to  camp.  Six 


THE    DEVELOPMENT    OF    COLORADO'S    MINING   INDUSTRY.  3 

of  the  party  went  east  to  procure  provisions,  returning  in  the 
spring  of  the  following  year,  1859. 

This  was  the  year  of  golden  discovery,  By  the  close  of  1858 
rumors  of  rich  diggings  had  crossed  the  plains,  the  rush  had 
set  in  and  crowds  began  to  arrive.  Among  these  came  John 
Hamilton  Gregory,  who,  with  J.  M.  Cotton  and  his  brother, 
William  Cotton,  went  up  Clear  creek  and  discovered  the  out- 
crop of  the  Gregory  lode  on  the  6th  of  May,  1859.  This  date 
is  the  birthday  of  Colorado's  mining  industry. 

The  discovery  of  the  Gregory  lode  was  immediately  followed 
by  that  of  other  veins,  whose  production  in  the  succeeding  years 
made  Gilpin  county  the  leading  gold  mining  district  of  the  Rocky 
mountains. 

In  the  meantime,  bands  of  prospectors  had  scattered  all 
over  the  neighboring  hills,  and  were  finding  the  gold  de- 
positories whose  later  developments  made  the  counties  of  Clear 
Creek,  Boulder,  Gilpin,  Summit,  Park  and  Lake  one  great 
mining  region. 

Boulder  was  contemporaneous  with  Gilpin.  In  1860  and 
1861  the  Columbia,  Ni  Wot,  Horsfal  and  Hoosier  veins  were 
discovered  and  brought  the  Ward  district  into  prominence.  A 
dozen  years  later  the  tellurides  of  Gold  hill  were  first  recog- 
nized in  the  ores  of  the  Red  Cloud  mine.  The  recognition  of 
their  true  character  led  to  the  successful  exploitation  of  the  rich 
ore-bodies  of  the  Magnolia,  Melvina,  Slide  and  John  Jay  mines, 
and  to  the  growth  of  the  hamlets  of  Sunshine,  Salina,  Provi- 
dence and  Magnolia.  The  Caribou  district  was  born  when 
Samuel  Conger  found  the  outcrop  of  the  Poorman  lode  in  the 
last  days  of  1869.  The  development  of  the  Caribou  vein  began 
in  the  succeeding  year. 

The  pioneers  who  followed  up  North  Clear  creek  (or  North 
Vasquez,  as  it  was  then  called)  and  founded  Gilpin's  industry 
also  wandered  up  the  north  fork  of  the  stream  and  discovered 
the  veins  whose  development  gave  wealth  to  Clear  Creek 
county.  In  August,  1858,  George  Jackson  did  some  prospect- 
ing .about  Vasquez  forks,  and  in  the  winter  of  that  year  he 
penetrated  to  Idaho  Springs  and  went  up  Chicago  creek.  On 
the  7th  of  January,  1859,  he  found  rich  gravel.  This  led  to 
active  search  and  successful  work  amid  all  the  other  tributaries 
of  Clear  creek.  The  diggers  followed  the  stream  to  its  head- 


4  THE    DEVELOPMENT    OF    COLOKADO'S    MINING    INDUSTRY. 

waters  amid  the  snows  of  the  main  range,  and  discovered  the 
veins  above  Silver  Plume  and  Georgetown.  The  sluicing  of 
the  soft  outcrops  of  certain  veins  served  as  a  link  leading  from 
placer  to  lode  mining.  The  Whale  above  Idaho  Springs  was 
one  of  the  finest  so  worked  in  1861.  In  the  upper  country,  near 
Empire,  the  gossan  of  the  Griffith  vein  was  successfully  sluiced 
in  1859.  The  silver-ores  were  also  recognized  about  that  time, 
the  Running  lode,  in  Gilpin  county,  having  attracted  attention 
to  the  white  metal  because  of  the  yield  of  a  peculiar  bullion 
rendered  intelligible  only  when  the  presence  of  silver  had  been 
determined.  The  silver-mining  industry  of  Upper  Clear  creek 
grew  to  important  dimensions  in  the  decade  succeeding  1870. 
The  Pelican  and  Dives  on  Republican  mountain  were  discov- 
ered in  1868,  but  did  not  commence  active  production  until 
1871.  The  Pay  Rock  was  found  in  1872.  The  mines  of  Sher- 
man mountain — the  Terrible,  Dunderberg,  Cory  City,  etc. — 
began  to  be  energetically  worked  early  in  the  seventies;  in 
Lower  Clear  creek,  John  Dumont  began  operating  the  Hukill 
in  1871.  In  1878  the  Hukill  and  Freeland  were  purchased  by 
J.  B.  Mackay  and  associates. 

The  mines  at  the  head  of  Virginia  canon  woke  to  life  by  the 
opening  up  of  the  Specie  Payment  in  1876. 

In  the  summer  of  1859  a  party  of  gold-seekers  followed  the 
Platte  from  the  foot-hills  through  its  gateway  into  the  South 
Park,  and,  camping  on  the  future  site  of  Fairplay,  they  crossed 
over  to  the  western  slope  and  descended  the  head-waters  of  the 
Blue  river.  Near  the  place  now  covered  by  the  town  of  Breck- 
enridge,  Reuben  Spalding  sunk  the  first  hole  that  disclosed  the 
riches  of  the  placers  of  the  Blue.  In  the  following  year  the 
gravels  of  its  tributary,  the  Swan,  were  prospected.  Alma  and 
Fairplay,  on  the  eastern  slope,  sprang  into  life  as  the  result  of 
the  alluvial  mining  which  then  began  a  productive  existence. 
It  was  not  until  1880,  however,  after  the  exhaustion  of  the  first- 
found  shallow  gold-bearing  gravel,  that  the  veins  of  Summit 
county  were  exploited.  The  placers  of  the  Blue  river  and  its 
tributaries  have  yielded  about  $35,000,000. 

So  were  born  the  mines  of  Clear  Creek,  Boulder,  Summit 
and  Park  counties.  But  more  wonderful  discoveries  were  in 
store.  Leadville  was  yet  to  be  uncovered. 

Among  the  scattering  bands  of  placer  diggers  who  spread 


THE    DEVELOPMENT    OF    COLORADO'S    MINING   INDUSTRY.  5 

over  the  ranges  in  1859,  one  party  followed  the  Arkansas  and 
camped  011  Georgia  bar.  In  the  following  spring  they  con- 
tinued up  the  river  and  divided  at  the  junction  of  California 
gulch  and  the  valley  of  the  Arkansas.  In  a  little  valley  lead- 
ing from  Iowa  gulch  they  stopped  at  noon.  In  breaking 
through  the  snow  to  get  water  for  their  coffee,  the  creek  had  been 
reached,  and  in  the  sand  John  O'Farrell  found  some  gold.  The 
pieces  of  porphyry  amid  the  gravel  reminded  the  discoverer  of 
similar  conditions  observed  on  the  Feather  river  in  California. 
Little  did  he  guess  the  significance  of  those  porphyry  fragments, 
or  the  enormous  wealth  which  that  rock  covered  on  the  neigh- 
boring hills.  This  was  April  6,  1860.  George  Stevens  and 
party  came  soon  after.  Their  discovery  claims  were  just  above 
the  site  of  the  A.  Y.  and  Minnie  mines.  Then  sprang  up  a 
placer-mining  industry  which  lasted  for  fifteen  years,  and  was 
only  obscured  by  the  greater  discoveries  which  ushered  in  an 
era  of  prolific  silver  mining. 

In  the  early  sixties  good  gold  veins  were  found  on,  Printer 
Boy  hill  overlooking  California  gulch.  These  mines,  of  which 
the  Printer  Boy,  Five-Twenty  and  Pilot  were  the  chief,  were 
productive  for  several  years  and  foreshadowed  the  development 
— thirty  years  later — of  the  gold  region  rendered  distinguished 
by  the  yield  of  the  now  celebrated  Little  Johnny  property. 

In  1874  W.  H.  Stevens  and  A.  B.  Wood  came  over  the  range 
from  Fairplay,  where  they  were  mining,  to  build  the  ore-ditch. 
When  examining  California  gulch,  Wood  found  float  consist- 
ing of  carbonate  of  lead  ore,  and  began  digging  on  the  south 
side,  now  known  as  Dome  hill,  on  what  was  afterward  the  Rock 
claim.  He  sank  a  little  shaft  through  the  drift,  which  covered 
the  outcrop,  at  a  point  subsequently  worked  by  an  open  cut. 
He  found  ore  in  place,  but  low  grade.  This  was  in  the  fall  of 
1875.  He  made  arrangements  to  have  some  work  done  that 
winter,  and  this  led  to  the  uncovering  of  the  outcrop  across 
California  gulch  up  Iron  hill.  The  next  year  the  whole  line  of 
outcrop-claims  was  located  on  the  supposed  veins,  and  ore  was 
taken  in  1877  from  the  Rock  claim  to  the  smelter  at  Malta, 
which  had  been  erected  three  years  before  to  treat  the  ores  of 
the  Homestake  mine.*  Stevens  got  Harrison  to  erect  reduction 
works  in  1877,  and  in  the  following  year  Mr.  James  B.  Grant 

*  Situated  on  the  Saquache  range  opposite  Leadville. 


6  THE    DEVELOPMENT    OF    COLORADO'S    MINING    INDUSTRY. 

put  up  the  establishment  from  which  in  later  years  grew  the 
magnificent  metallurgical  industry  of  the  Omaha  &  Grant  Smelt- 
ing and  Refining  Company. 

In  1878,  also,  George  Fryer  sunk  a  hole  on  a  hill  north  of 
Stray  Horse  gulch,  and  found  carbonate  ore,  uncovering  in  this 
act  the  great  ore-measure  which,  as  "  the  first  contact  "  proved, 
was  one  of  the  most  remarkable  bodies  of  ore  known  in  mining 
geology.  A  month  later  Eische  and  Hook  happened  to  sink  a 
hole  where  the  contact  approached  the  surface,  and  found  the 
ore-body  which  subsequently  became  the  Little  Pittsburgh 
mine,  and  the  foundation  of  Tabor's  fortune.  Other  discove- 
ries followed  fast,  That  year — 1878 — Leadville's  output  ex- 
ceeded in  value  3,000,000.  In  1887  it  culminated  in  an  output 
estimated  to  be  worth  $13,500,000.  Up  to  date  its  yield  has 
been  $215,000,000. 

In  the  meantime  other  mining  camps  were  being  born.  In 
the  fall  of  1872  veins  were  found  near  Rosita,  in  Custer  county, 
and  in  1877  the  Bassick  began  to  produce,  creating  the  excite- 
ment of  Silver  cliff. 

Among  the  progeny  of  the  Leadville  boom  were  Kokomo  and 
Robinson,  in  the  Ten-Mile  district,  whose  checkered  career  be- 
longs to  later  days. 

In  the  meantime  the  mining  industry  of  Colorado  was  going 
through  the  troubles  of  its  early  youth.  The  history  of  Gilpin 
county  is  so  typical  of  this  phase  of  its  development,  that  I  have 
reserved  it  for  special  description. 

Following  upon  Gregory's  discovery,  other  veins,  subse- 
quently famous,  were  found.  On  the  15th  of  May,  the  Bates 
lode  was  uncovered,  on  the  25th  the  Gunnell,  Kansas  and  Bor- 
roughs.  The  Bobtail  was  discovered  in  June.  The  early  min- 
ing operations  consisted  of  the  removal  of  the  soft  decomposed 
croppings  which  were  washed  in  the  sluices  after  the  fashion  of 
ordinary  placer  mining.  The  harder  outcrops  were  crushed 
under  trip-hammers  until  arrastras  were  introduced,  to  give 
way  in  their  turn  to  primitive  stamp-mills.  By  the  1st  of  July, 
1860,  there  were  60  mills  in  operation.  Everything  proceeded 
serenely.  But  the  gossan  gave  way  to  pyritic  ore  as  the  dis- 
covery shafts  penetrated  deeper.  The  saving  of  the  gold  became 
more  difficult.  In  spite  of  these  drawbacks,  the  richness  of  the 
upper  portions  of  the  first-found  lodes  was  such  as  to  leave  a 


THE    DEVELOPMENT    OF   COLORADO'S    MINING   INDUSTRY.  7 

handsome  margin  and  maintain  a  steadily  growing  population. 
In  the  winter  of  1863,  and  the  spring  of  1864,  several  mines 
were  sold  in  New  York  and  Boston.  A  stock  mania  super- 
vened, only  to  collapse  suddenly  in  April.  At  this  time  also 
came  the  period  of  incoherent  processes,  with  the  promise  of 
100  per  cent,  extraction.  Some  of  their  progeny  still  survived, 
uttering  claims  nearly  as  magnificent.  The  inexperienced, 
chemist,  with  his  revelation  for  cheap  ore-reduction,  continued 
what  the  stock-jobber  had  begun.  The  mining  industry  of  Gil- 
pin  was  crippled  unto  death. 

At  this  time  the  easily  amalgamated  surface-ores  had  in  many 
instances  become  exhausted,  giving  place  to  hard  pyritic  mate- 
rial, which  refused  to  yield  up  its  contained  gold.  Extraction 
in  the  stamp-mills  continued  to  become  worse.  Many  mines 
were  compelled  to  close  down,  others  were  operated  at  a  ruin- 
ous loss  of  the  gold  in  their  ores.  A  depression  fell  upon  the 
district,  which  was  not  removed  until  1868,  when  a  general  re- 
vival began.  The  leasing  of  claims  by  working  miners  led  to 
new  discoveries,  and  the  consolidation  of  adjoining  territory 
diminished  expenses.  At  this  time  the  smelter  came  to  the 
rescue  of  the  baffled  mill-man.  In  1867  the  Boston  and  Colo- 
rado Smelting  Company  was  organized  by  Professor  ~N.  P.  Hill. 
In  June  the  first  experimental  plant  was  erected  at  Black  Hawk. 
In  January,  1868,  the  establishment  opened  for  business.  In 
1873  the  company  ceased  the  shipment  of  matter  to  Swansea, 
and  erected  a  refinery  under  the  direction  of  Mr.  Richard  Pearce. 
In  1870  the  smelter  moved  to  Denver. 

This  represents  a  stage  of  progress  common  to  all  our  mining 
regions.  Crude  milling  methods  gave  way  to  fine  reduction 
processes,  and  the  latter,  by  their  heavy  charges,  invite  the  mill- 
man  to  improve  on  his  cheaper  methods,  so  that  competition  is 
restored.  The  Black  Hawk  smelter  saved  the  mining  industry 
of  Gilpin  county  when  it  was  on  the  verge  of  utter  collapse. 
And  on  the  restoration  of  prosperity,  the  owners  of  the  stamp- 
mills  were  enabled  to  carry  on  experiments  whose  expense  was 
met  by  the  sale  of  ore  to  the  smelter,  so  enabling  them  to  evolve 
a  method  of  stamp-milling  which  was  well  adapted  to  the  treat- 
ment of  the  heavy  pyritic  ores  produced  by  their  mines.  In 
1871  the  problem  had  been  solved,  and  to-day  500  stamps  do 
excellent  work  with  the  low-grade  ore  of  the  district. 


8  THE    DEVELOPMENT    OF    COLORADO'S    MINING    INDUSTRY. 

Grilpin  county  has  produced  about  $68,000,000  to  date. 

While  these  problems  were  undergoing  solution,  mining  was 
winning  fresh  territory  southward,  amid  that  great  complex  of 
mountains  whose  waters  drain  into  the  San  Juan  river.  A 
party  of  pioneers,  guided  by  Jim  Baker,  crossed  the  Sangre  de 
Cristo  range  and  reached  the  head-waters  of  the  Anirnas  in 
1861.  In  spite  of  snow-slides  and  Indians  the  search  for  gold 
and  silver  was  extended  over  the  neighboring  ranges.  The 
ratification  of  the  Brunot  treaty,  in  1873,  marked  the  cession  of 
this  part  of  the  territory  by  the  Indians,  and  removed  one  of 
the  most  serious  obstacles  to  the  development  of  the  region. 
In  the  meanwhile,  mines  were  being  opened  up  on  every  side. 
The  Baker  party  tested  the  river  gravels,  and  the  evidences  of 
their  placer-workings  still  remain  in  many  a  secluded  valley  to 
tell  of  their  first  beginnings.  In  the  spring  of  1871  lode-mining 
may  be  said  to  have  commenced  by  the  discovery  and  location 
of  the  Little  Giant  vein,  just  above  the  present  town  of  Silver- 
ton,  by  Miles  T.  Johnson.  In  the  following  year  an  arrastra  was 
built,  and  the  gold  thus  extracted  out  of  the  ore  was  taken  for 
sale  to  Conejos,  the  nearest  trading  station.  In  1874  Judge 
Green,  of  Cedar  Rapids,  la.,  commenced  the  erection  of  a  smel- 
ter, the  machinery  of  which  came  on  burro-back  from  Colorado 
Springs,  where  the  Denver  and  Rio  Grande  railroad  had  just 
reached.  The  ore  supply  of  this  smelter  came  principally  from 
the  Aspen,  which  at  that  time  was  the  chief  mine  in  the  locality. 

In  1875  Mr.  J.  A.  Porter,  the  metallurgist  of  Green  &  Co.'s 
smelter,  introduced  the  syphon-tap,  and  in  the  following  year 
he  erected  the  first  water-jacketed  furnace  built  in  Colorado. 

The  prospectors  who  made  Silverton  their  headquarters  scat- 
tered up  the  valley  of  Mineral  creek,  and  on  the  watershed 
separating  this  tributary  of  the  Animas  from  the  Uncompaghre 
found  the  veins  which  gave  fame  to  Red  mountain.  In  1879, 
Charles  Newman  and  Harry  Irving  located  the  Carbon  Lake 
claim,  and  did  their  annual  assessment  until  1882,  when  a  dis- 
covery of  copper-ore  was  made  on  the  adjoining  Congress 
claim  and  shipments  began. 

In  August  of  the  same  year,  Andrew  Meldrum,  while  out 
hunting,  stumbled  upon  the  outcrop  of  galena  which  marked 
the  now  famous  Yankee  Girl  vein.  The  American  Belle  and 
Guston  were  discovered  shortly  afterwards.  Five  years  later 


THE    DEVELOPMENT    OF    COLORADO'S    MINING   INDUSTRY.  9 

this  district  became  a  magnificent  producer  of  very  rich  copper- 
ores.  In  1894  a  smelter  was  erected  at  Silverton  to  treat  the 
product  of  the  region. 

In  the  meanwhile,  Gus  Begole  had  crossed  the  western  range 
from  Silverton,  and  descending  into  the  valley  of  the  Dolores, 
located  claims  which  later  became  the  Yellow  Jacket  and  Aztec 
mines.  But  the  ore  was  too  low  in  grade  and  the  work  soon 
ceased. 

In  1878  John  Glasgow  and  Sandy  Campbell  came  northward 
from  La  Plata  City,  and  began  the  successful  development  of 
the  Grand  View  and  Atlantic  Cable,  causing  the  growth  of  the 
town  of  Rico.  The  news  was  spread  abroad  that  another  Lead- 
ville  had  been  found,  and  crowds  trooped  in  across  the  hills  dur- 
ing the  summer  of  1879.  In  the  fall  of  1880  the  smelter  began 
operations.  Nevertheless  the  district  would  have  gained  but 
slight  distinction,  had  not  the  ore-deposits  of  Newman  hill  been 
found.  These  began  to  be  productive  when,  on  the  6th  of  Oc- 
tober, 1887,  David  Swickheimer  struck  the  big  ore-body  of  the 
Enterprise  mine. 

In  June,  1870,  gold  was  found  in  Wightman's  gulch.  This 
led  to  the  location  of  the  Little  Annie  in  September,  1873,  and 
the  opening  up  of  the  Summitville  district,  which  is  tributary 
to  Del  Norte,  whose  position  made  it  a  natural  gateway  to  the 
watershed  of  the  Rio  Grande. 

Among  the  old  districts  recently  revived  is  the  La  Plata 
mountain  region,  north  of  Durango  and  south  of  Rico.  In 
1873,  Captain  John  Moss,  representing  Tiburcio  Parrott  and 
other  San  Francisco  capitalists,  came  up  the  San  Juan  river 
from  Arizona  and  penetrated  the  La  Plata  mountains,  being 
attracted  thither  by  the  gold-bearing  gravel  of  the  streams.  He 
followed  the  latter  to  their  source  and  discovered  a  large  num- 
ber of  veins.  The  Comstock,  Morovitz,  Euclid  and  Ashland 
claims  were  located  at  that  time.  La  Plata  City  was  founded, 
and  great  activity  characterized  the  camp  for  a  brief  period. 
But  the  complex  telluride  ores  proved  refractory;  and  the 
arrastra  was  found  to  be  powerless  to  extract  the  values.  Great 
expectations  had  a  sequel  of  small  accomplishment.  The  dis- 
trict became  depopulated.  In  1894  new  discoveries  were  made, 
and  a  revival  took  place,  leading  to  more  serious  work,  which 
now  promises  better  things. 


10    THE  DEVELOPMENT  OF  COLORADO^  MINING  INDUSTRY. 

And  so  we  come  to  recent  times,  no  less  stirring  than  the  old. 
The  history  of  the  last  decade  centers  round  the  discovery  of 
Aspen,  the  stories  of  Creede  and  of  Cripple  Creek,  the  collapse 
of  silver  mining  and  the  development  of  new  gold-fields. 

The  first  discovery  in  the  Roaring  Fork  district,  of  which 
Aspen  is  the  center,  was  made  July  3,  1879,  when  Phillip 
W.  Pratt  and  Smith  Steel,  coming  from  Gothic  by  the  Ma- 
roon pass,  found  the  Galena  mine  on  West  Aspen  mountain. 
On  the  following  day  they  located  the  Spar  claim  on  Aspen 
mountain,  and  on  the  5th  Messrs.  Allbright  and  Fuller  located, 
at  the  foot  of  Smuggler  mountain,  the  Little  Rock  claim,  cover- 
ing a  part  of  the  property  of  the  present  Smuggler  mine.  The 
Smuggler  claim  itself  was  located  August  30th,  by  Charles  Ben- 
nett. On  account  of  the  theft  of  the  first  four  pages  of  the 
district  recorder's  book,  it  became  necessary  to  make  reloca- 
tions, which  now  appear  on  the  records  at  Gunnison,  the  dis- 
trict being  then  a  part  of  Gunnison  county. 

The  first  mineral  survey  was  made  on  the  Monarch  mine, 
October  12,  1879,  by  John  Christian,  of  Leadville.  The  site 
of  the  present  city  of  Aspen  was  devastated,  in  September  of 
that  year,  by  a  forest-fire,  in  which  many  horses  and  pack-mules 
were  lost.  An  Indian  scare,  following  the  Meeker  massacre, 
caused  most  of  the  prospectors  to  leave  the  camp ;  but  a  suffi- 
cient number  remained  to  build  log-cabins  on  the  site  now  oc- 
cupied by  Aspen,  which  was  located  as  a  placer-claim  Septem- 
ber 20,  1879,  by  Walter  Clark. 

It  was  not  until  ten  years  later  that  the  new  district  won  a 
commanding  position.  At  that  time  (1889)  the  Aspen,  Aspen 
Compromise  and  Compromise  mines  maintained  a  large  out- 
put, and  it  was  in  1891  that  the  big  bonanza  of  the  Mollie  Gib- 
son was  uncovered.  Aspen  is  credited  with  a  production  of 
8,275,000  ounces  of  silver  in  the  year  1892. 

!N".  C.  Creede  found  the  float  of  the  Holy  Moses  vein,  on  West 
Willow  creek,  a  tributary  of  the  Rio  Grande,  in  1889.  As  a 
consequence,  the  King  Solomon  district,  as  it  was  then  called, 
began  to  attract  the  prospectors  scattered  in  the  mountains 
above  Del  Norte.  No  important  results  ensued  until  in  June, 
1891,  D.  H.  Moffat  and  Capt.  L.  E.  Campbell  came  to  Wagon 
Wheel  gap  to  visit  the  Holy  Moses,  on  which  they  had  secured 
an  option.  Creede  was  engaged  to  prospect  for  them.  Shortly 


THE  DEVELOPMENT  OF  COLORADO^  MINING  INDUSTRY.    11 

afterwards,  Theodore  Renniger  found  rich  float  on  Bachelor 
mountain.  He  was  unsuccessful  in  finding  the  vein  in  place  until 
Creede  came  along,  and,  at  a  point  200  feet  higher  up  on  the 
hill-slope,  discovered  the  outcrop  of  a  large  lode.  He  located 
the  Amethyst  claim  and  then  informed  Renniger,  who  took  up 
on  the  same  vein  another  claim,  which  he  called  the  Last 
Chance.  This  was  on  the  8th  of  August,  1891.  It  should  be 
added  that,  three  years  previously,  J.  C.  McKenzie  had  located 
several  claims  on  a  heavy  quartz  outcrop,  about  150  feet  above 
the  Amethyst.  These  were  afterwards  abandoned  until  the 
fall  of  1891,  when  the  Del  Monte  location  covered  them.  Debris 
from  the  upper  portions  of  the  mountain  had  so  obscured  the 
outcrop  of  the  Amethyst  that  its  earlier  recognition  had  been 
prevented.  After  Creede's  discovery  but  little  work  was  re- 
quired to  prove  the  existence  of  a  magnificent  lode,  and,  as  a 
consequence,  the  camp  sprang  into  tremendous  activity,  cul- 
minating in  the  boom  of  1892.  The  immediate  extension  of 
the  railway  from  Wagon  Wheel  gap  stimulated  a  production 
which  reached  its  maximum  in  an  output  of  $3,100,000.  Then 
in  the  summer  of  1893  came  the  sudden  fall  in  silver  and  a 
collapse  from  which  Creede  has  not  yet  recovered. 

Creede  and  Cripple  Creek  were  rivals  in  attracting  attention 
in  1891.  Both  have  had  strange  vicissitudes.  Our  new  gold- 
field  lies  on  the  southern  slope  of  Pike's  Peak,  whose  snow-clad 
crest  was  the  beckoning  guide  of  the  pioneers  of  1858.  Al- 
though no  gold  discoveries  of  any  moment  were  made  in  the 
early  days  among  the  streams,  or  on  the  hills  lying  at  the  foot 
of  the  old  beacon  mountain,  it  nevertheless  gave  its  name  to  the 
mining  excitement  of  that  period.  Time  has,  however,  of  late, 
justified  the  expectations  of  the  tenderfeet  of  forty  years  ago. 

The  first  recorded  locations  were  made  in  February,  1891, 
but  the  clustering  hills  which  are  now  dotted  with  productive 
mines,  had  been  disturbed  by  the  miner's  pick  as  early  as  1874. 
Silver-ores  were  found  in  a  shaft  located  close  to  the  present 
Elkton  mine.  Ores,  rich  in  the  white  metal,  had  been  found  in 
late  years,  and  the  Moose  made  one  shipment  of  30  tons,  carry- 
ing an  average  of  70  ounces  of  silver,  in  addition  to  the  gold. 

Ten  years  afterward,  in  April,  1894,  the  district  was  the 
scene  of  the  queer  fiasco  which  has  gone  into  local  history  as 
the  Mt.  Pis^ah  excitement.  A  crowd  of  4000  men  were 


12        THE    DEVELOPMENT    OF    COLORADO'S    MINING   INDUSTRY. 

brought  together  on  the  rumored  discovery  of  rich  placer 
ground.  Nothing  was  found  save  in  the  holes  of  the  original 
locators.  Man  had  endeavored  to  remedy  nature's  niggardli- 
ness and  the  poor  rock  had  been  artificially  enriched.  Lynch- 
ing was  threatened,  but  in  the  failure  to  catch  the  perpetrator 
a  big  picnic  took  place,  after  which  the  hill  slopes  again  became 
the  quiet  cattle  ranges  for  which  they  seemed  best  adapted. 
Those  deluded  prospectors  let  slip  a  great  opportunity.  Mt. 
Pisgah's  dark  front  now  overshadows  the  busy  streets  of  the 
town  of  Cripple  Creek,  and,  on  the  ridges  opposite,  line  after 
line  of  smoking  chimneys  bespeak  a  long  succession  of  pro- 
ductive mines. 

During  the  spring  of  1891  Cripple  Creek  began  to  receive 
respectful  mention  in  mining  circles,  but  the  discoveries  made 
at  Creede  during  that  summer  diverted  attention  from  a  dis- 
trict whose  previous  experience  had  given  it  an  unsavory  repu- 
tation. When,  however,  the  silver  market  collapsed  in  June, 
1893,  and  mining  seemed  prostrated,  the  men  of  Aspen  and 
Leadville  turned  with  the  energy  of  despair  to  the  new  gold 
field  which  previously  had  been  pooh-poohed,  and  the  concen- 
trated activities  of  the  State  were  directed  to  the  development 
of  Cripple  Creek.  With  a  rare  good  fortune,  the  new  camp 
answered  to  the  call,  and,  as  explorations  extended,  there  came 
a  swift  succession  of  rich  discoveries  which  caused  the  output 
to  spring  from  $583,000  in  1892  to  $2,100,000  in  1893.  This 
growth  continued  so  that  in  1894  the  yield  was  $3,900,000,  and 
in  1895  it  reached  $7,800,000.  These  figures  are  sufficiently 
eloquent  of  the  development  of  a  district  which  to-day  is  the 
largest  producer  of  all  the  gold-mining  camps  of  the  United 
States. 

During  the  past  three  years  discoveries  in  other  parts  of  the 
State  have  received  mention,  and  large  claims  have  been  made 
in  behalf  of  several  new  districts.  West  Creek,  Cottonwood, 
Hahn's  Peak  and  the  Gunnison  region  may  be  cited.  Of  these 
the  last  named  is  much  the  most  important.  At  the  head-waters 
of  certain  streams,  tributary  to  the  Gunnison  river,  there  have 
been  found  veins  which  are  now  supplying  several  stamp  mills 
with  pay-ore,  and  have  given  birth  to  the  settlements  of  Vulcan, 
Spencer,  Iris  and  Dubois. 

While  the  new  territory  which  has  been  won  during  later 


THE    DEVELOPMENT    OF    COLORADO'S    MINING   INDUSTRY.          13 

days  adds  its  tribute  of  gold  and  silver  to  the  yield  of  the  old 
established  mining  centers,  it  must  be  noted  that  the  latter  have 
also  accommodated  themselves  to  new  economic  conditions. 
The  Silverton  district,  in  the  southwest,  for  instance,  which  in 
1892  yielded  gold  worth  $155,624,  and  silver  valued  at  $354,- 
125,  gave  in  1894  gold  amounting  to  $360,320,  and  silver  worth 
$235,000.  This  is  typical  of  the  changed  conditions  regulating 
the  industry.  It  is  a  striking  evidence  of  that  resourcefulness 
which  has  enabled  the  State  to  overcome  difficulties.  The  col- 
lapse of  the  silver-mining  led  directly  to  an  impetus  in  the 
search  for  gold,  and  the  variety  of  ores  so  puzzling  in  the  in- 
fancy of  our  smelting  industry,  is  to-day  its  chief  aid,  because 
it  enables  the  attainment  of  that  admixture  of  material  which 
is  the  essential  of  successful  reduction. 

Colorado  has  yielded  to  date  gold  valued  at  $137,475,000, 
and  silver  having  a  coinage-value  of  nearly  $400,000,000. 

Thus,  from  humble  beginnings,  a  great  and  complicated  in- 
dustry has  been  created.  Its  development  may  be  summarized 
in  four  periods :  The  discoveries  in  Gilpin  county  and  the  ad- 
joining camps  in  the  granite 'rocks  of  the  front  range,  the  era 
of  silver-mining  in  the  carboniferous  limestones  of  Leadville, 
Aspen  and  Rico,  the  development  of  the  fissure  veins  in  the 
andesites  of  the  San  Juan,  and  lastly,  the  revival  of  gold-min- 
ing consequent  upon  the  uncovering  of  a  great  series  of  ore- 
deposits  in  the  volcanic  complex  of  the  Pike's  Peak  region. 


SUBJECT  TO   REVISION. 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


Gold-Milling  in  the  Black  Hills,  South  Dakota,  and  at 
Grass  Valley,  California. 

BY  T.    A.    RICKARD,    DENVER,   COLORADO. 

(Atlanta  Meeting,  October,  1895.) 

OUR  Transactions  contain  two  notable  papers  descriptive  of 
the  stamp-milling  practice  of  the  Black  Hills  and  of  Grass 
Valley,  namely,  the  elaborate  and  complete  treatise  of  Prof.  H. 
O.  Hofman,  on  «  Gold-Milling  in  the  Black  Hills,"*  and  the 
paper  describing  the  North  Star  mill,  by  E.  R.  Abadie,  its 
superintendent. f  Having  visited  and  examined  the  stamp- 
mills  of  both  localities,  I  venture  to  offer  here  such  comment 
as  more  recent  information  or  a  different  point  of  view  has 
suggested.  | 

I. — THE  BLACK  HILLS. 

Prof.  Hofman's  paper  was  prepared  in  1888,  seven  years  ago, 
yet  the  methods  in  vogue  to-day  at  Lead  City  and  Terraville 
do  not  differ  materially  from  those  so  carefully  described  by 
him. 

The  mining  industry  of  the  Black  Hills  is  not  so  actively 
prosperous  in  1895  as  it  was  in  1888.  Not  so  many  stamps  are 
dropping ;  some  of  the  mines  have  been  compelled  to  suspend 
operations  owing  to  a  falling  off"  in  the  yield  of  ore,  while  others 
have  passed  into  the  comprehensive  control  of  the  Homestake 
management.  Nevertheless,  the  mines  and  mills  of  the  Belt 
produce  more  gold  than  any  other  single  mining  camp  in  the 
United  States,  with  the  exception  of  Cripple  Creek,  Colorado. 

*  Trans.,  xvii.,  498.  f  Id.,  xxiv ,  208. 

1  For  more  detailed  descriptions  and  discussions,  I  would  refer  to  a  series  of 
papers  on  "Variations  in  the  Milling  of  Gold-Ores,"  which  I  have  contributed  to 
the  Engineering  and  Mining  Journal  during  the  present  year,  and  from  which  quo- 
tations are  made,  and  statistical  material  is  reproduced  in  the  present  paper.  The 
illustrations  herewith  given  will  be  found,  with  others,  in  the  Journal  of  Septem- 
ber 7  and  14,  1895,  and  are  here  used  through  the  courtesy  of  the  Scientific  Pub- 
lishing Company. 


Z       GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

The  Belt  is  that  part  of  the  region  contiguous  to  the  Home- 
stake  lode  and  its  extensions,  and  reaching  from  Whitewood 
creek  to  Dead  wood  gulch.  It  is  the  center  of  the  mining  ac- 
tivity of  the  Black  Hills,  the  only  important  mining  region  in 
the  State  of  South  Dakota. 

The  geological  relations  of  the  ores  of  the  district  have  been 
referred  to  in  our  Transactions  by  W.  B.  Devereux*  and  F.  B. 
Carpenter,  respectively,  f  It  is  to  be  regretted  that  so  important 
and  interesting  an  ore-deposit  as  the  Homestake  vein  should 
not  have  undergone  long  ago  more  detailed  description  at  the 
hands  of  some  one  of  our  members.  The  commercial  environ- 
ment of  mining  enterprises  often  militates  against  scientific  in- 
vestigation. 

While  the  writer  has  not  had  an  opportunity  of  making  a 
careful  examination  of  the  mines,  a  visit  underground  was 
sufficient  to  show  the  justification  for  the  great  ore-reduction 
establishments  of  the  Homestake  Mining  Co.  The  ore  occurs 
in  large  bodies  of  quartzified  chloritic  schists,  conforming  to 
the  structure  of  the  country  and  being  a  portion  of  it.  The 
width  of  milling-ore  varies  from  50  to  400  feet.  Most  of  the 
supply  comes  at  present  from  above  the  500-foot  level ;  but  the 
developments  in  lower  levels,  down  to  the  800-foot,  indicate  the 
continuity  of  the  enormous  ore-shoots  of  the  mine.  The  huge 
excavations  made  along  the  outcrop  of  the  lode  (See  Fig.  1), 
are  a  distinctive  feature  of  the  present  topography  of  the  Belt, 
and  bear  impressive  witness  to  the  immense  quantities  of  mill- 
stuff  that  have  gone  under  the  stamps.  Extensive  bodies  of  ore 
are  still  held  in  reserve  in  these  surface  open-cuts. 

Behind  the  Highland  shaft-house  there  is  a  large  cut,  which 
gives  a  very  excellent  section  of  the  geological  formation, 
showing  the  uptilted  edges  of  the  gold-bearing  schists,  overlain 
by  Cambrian  sandstone.  The  latter,  only  a  few  feet  thick  at 
this  point,  is  split  by  an  intruding  sheet  of  the  porphyry  which 
also  overlies  the  whole  formation  and  caps  the  hilltop.  The 
lowermost  member  of  the  Cambrian  series  is  a  conglomerate, 
identified  by  its  fossils  as  belonging  to  the  Potsdam  period,  and 
said |  to  have  been  derived  from  the  degradation  of  the  gold- 

*  Trans.,  x.  465.  f  Id.,  xvii.,  570. 

%  By  Devereux,  Trans.,  x.,  966,  et  seq.     The  development  of  the  conglomerates 
of  the  Witwatersrand  adds  much  interest  to  these  Dakota  deposits. 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       3 

bearing  lode  under  the  outcrop  of  which  it  was  formed  by  the 
seas  of  a  very  early  geological  time.  These  facts  indicate  for 
the  Homestake  vein  an  origin  of  remarkable  geological  an- 
tiquity. 

The  porphyry  above  mentioned  is  a  felsite.  At  one  time  it 
was  broken  with  the  ore  and  sent  to  the  mills  in  spite  of  its 
valueless  character.  Kow  it  is  used  for  filling  up  stopes.  Un- 
derground it  can  be  seen  in  dikes  conformable  to  the  vein- 
walls,  and  splitting  the  ore-bodies  by  its  intrusion. 

The  first  mill  in  the  Black  Hills  was  that  erected  by  the 
Racine  company,  at  the  lower  end  of  Lead  City,  in  April,  1877. 
The  beginning  of  the  mining  industry  of  the  Black  Hills  dates 
back  to  June,  1876,  when  the  Wheeler  brothers  found  rich 
gravel  in  Deadwood  gulch.  The  outcrops  of  the  large  quartz- 
lodes  were  early  seen,  but  quickly  discarded  by  the  California 
and  Montana  miners,  who  ridiculed  the  idea  of  the  profitable 
handling  of  ores  which  yielded  on  panning  only  from  three  to 
ten  dollars  per  ton. 

After  the  placer-mines  had  commenced  to  yield  handsomely, 
and  while  the  quartz-lodes  were  unappreciated,  the  early  min- 
ing activity  was  diverted  to  the  development  of  the  lowermost 
beds  of  the  Potsdam  formation,  the  gold  of  which  lay  in  a 
conglomerate.  It  was  to  reduce  this  conglomerate  that  the 
first  stamp-mills  were  introduced.  They  were  of  the  primitive 
Colorado  pattern,  and  proved  entirely  unsuited  to  the  extraction 
of  gold  from  such  material.  They  made  a  poor  record,  and 
were  followed  by  the  fast-dropping  stamps,  modeled  on  Califor- 
nian  practice,  first  introduced  by  Mr.  Augustus  J.  Bowie,  Jr., 
in  his  design  of  the  Father  de  Smet  mill,*  the  erection  of 
which,  at  Terraville,  was  commenced  in  June,  1878.  This 
plant  was  succeeded  by  the  first  of  the  Homestake  Co.'s  mills, 
which  also  had  a  narrow  mortar  and  a  rapid  discharge.  The 
Caledonia,  erected  the  following  year,  used  more  roomy  mortars 
and  two  inside  amalgamating-places,  more  after  the  Colorado 
fashion.  This  mill  is  now  idle,  chiefly  for  lack  of  suitable 
ore-supply,  and  therefore  a  comparison  between  the  two  styles 
of  working  is  not  possible.  ISTevertheless,  I  do  not  hesitate  to 
say  that  the  Homestake  mortar,  deep  and  narrow,  gives  a  com- 

*See  Trans.,*.,  87. 


4       GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 


bination  for  rapid  pulverization  and  high  percentage  of  extrac- 
tion inside  the  battery  which  render  it,  for  the  ores  of  this 
district,  far  superior  to  any  other  mortar  I  know. 

All  the  mills  now  at  work  on  the  Belt  are  under  the  direc- 
tion of  the  Homestake  management,  with  the  exception  of  the 
little  10-stamp  Columbus  mill  at  Central  City.  When  Prof. 
Hofman  wrote  his  paper,  there  were  660  stamps  dropping  on 
the  free-milling  ores  of  the  Belt;  to-day  the  number  is  550. 
The  Be  Smet  and  Caledonia  mines  have  been  unable  to  sur- 
vive a  diminution  in  the  tenor  of  the  ores  they  produced,  and 
the  mills  belonging  to  them  have  ceased  operations,  the  former 
in  1892  and  the  latter  in  1893.  The  Highland  Co.'s  mill  has 
been  lately  increased  by  the  addition  of  20  stamps.  The  Golden 
Terra  and  Deadwood  mills  were  consolidated  six  years  ago,  the 
80  stamps  of  the  Terra  being  placed  behind  the  80  stamps  of 
the  old  Deadwood  mill.  The  two  large  mills  of  the  Home- 
stake  Co.  have  undergone  steady  enlargement,  and  in  addition 
to  the  number  of  stamps  given  in  the  annexed  table,  there  are 
40  about  to  be  added  to  the  Golden  Star  mill,  whose  total  will 
then  be  200  stamps. 

TABLE  L—  The  Stamp  Mills  of  the.  Belt,  South  Dakota. 


Name. 

d 

c§W 
P 

Location. 

Number  of 
Stamps. 

Owners. 

Homestake  

1878 
1879 
1880 
1879 
1880 
1878 
1879 
1894 

Lead  City. 
Lead  City. 
Lead  City. 
Terraville. 
Terraville. 
Central  City. 
Terraville. 
Central  City. 

1888. 

801 

120  / 
120 
801 
80  j 

100 

80 

1895. 
100  \ 
160  / 
140 

160  } 

100 

80 
10 

The  Homestake  Mining 
Co. 
The  Highland  Mining  Co. 
The       Deadwood  -  Terra 
Mining  Co. 
The  F.  de  S.  Mining  Co. 
The  Caledonia  Min.  Co. 

Golden  Star  
Highland  

Deadwood 

Golden  Terra  
Father  de  Smet. 
Caledonia  

Columbus  

The  ore  is  dumped  at  the  shaft's  mouth  into  the  rock- 
breakers.  At  the  time  of  Prof.  Hofman's  investigations,  all 
the  Homestake  mills  were  using  the  Blake,  and  the  Caledonia 
had  just  introduced  a  Gates  crusher.  Since  that?  time  the 
Gates  has  replaced  the  Blake  rock-breaker  in  every  mill  on  the 
Belt.  Furthermore,  the  rock-breaker  is  now  placed  in  the 
shaft  house  instead  of  at  the  mill.  This  follows  the  teiiden- 


GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       5 

cies  of  modern  practice  in  California,  where  the  crusher  at  the 
mine  delivers  the  broken  ore  to  the  tramway,  which  carries  it 
to  the  mill,  or  sometimes  to  a  second  rock-breaker.  The  latter 
arrangement  relieves  the  stamps  of  the  hard  work  of  stone 
breaking,  facilitates  pulverization  in  the  mortar  and  gives  uni- 
form conditions  more  favorable  to  successful  amalgamation. 

The  transference  of  the  rock-breaker  from  the  mill  to  the 
mine  is  in  itself  a  praiseworthy  change.  It  enlarges  the 
capacity  of  the  ore-bins  at  the  mill,  and  renders  unnecessary 
the  use  of  separate  bins  for  coarse  and  fine.  In  small  plants 
where  the  breaker,  if  at  the  mill,  would  not  be  driven  by  a 
separate  engine,  it  does  away  with  that  irregularity  in  the  work- 
ing of  the  mill  arising  from  the  unequal  consumption  of  power 
on  the  part  of  a  rock-breaker.  It  renders  easy  the  loading  of 
the  cars  which  bring  the  ore  from  the  mine,  a  factor  important 
in  the  case  of  aerial  rope-ways  carrying  buckets  of  small 
capacity.  But  more  important  than  these  minor  advantages  is 
the  almost  entire  cessation  of  the  production  of  the  dust  so  in- 
jurious to  all  the  mechanism  of  the  mill  and  always  such  a 
nuisance  to  those  who  work  in  it. 

Most  of  the  mills  use  the  No.  6  Gates  breaker.  The  Dead- 
wood-Terra  and  Highland  have  two  each.  The  Homestake 
mine  has  three,  one  of  which  is  held  in  reserve  to  avoid  delay 
due  to  repairs  on  either  of  the  others.  Experience  has  shown 
that  the  larger  receiving  capacity  of  the  Gates  and  its  greater 
crushing  power  render  it  more  suitable  for  large  milling-estab- 
lishments than  the  Blake. 

Prof.  Hofman  has  described  the  various  methods  for  trans- 
mitting the  power  to  the  different  parts  of  the  mill.  Of  these, 
the  arrangement  in  the  Golden  Star  mill  resembles  that  in 
vogue  in  California  and  in  the  best  Colorado  mills.  The  driv- 
ing-shaft is  approximately  level  with  the  cam-shaft,  and  the 
connecting-belts  are  nearly  horizontal.  The  latter  are  in  a 
place  easily  accessible,  well  lighted  and  away  from  the  dirt  and 
water  inseparable  from  the  close  neighborhood  of  the  battery 
itself.  Such  an  arrangement  requires  that  the  sills  under  the 
cam-floor  shall  be  made  stronger  than  if  they  simply  supported 
the  flooring,  but  the  additional  expense  is  trifling  compared  to 
the  convenience  of  the  plan.  On  the  other  hand,  the  placing 
of  the  counter-shaft  immediately  underneath  the  feeder-floor, 


6       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

an  addition  to  the  inaccessibility  and  inconvenience,  the  environ- 
ment of  dirt  and  water,  the  absence  of  light,  etc.,  requires  the 
use  of  tighteners  injurious  to  the  belting.  The  Star  mill  uses 
one  belt  while  the  Highland  wears  out  three. 

All  the  batteries  are  placed  upon  flat  sites  in  two  rows  back 
to  back,  save  at  the  Father  de  Smet,  where  the  two  rows  of 
batteries  face  each  other  and  discharge  toward  the  center  of  the 
mill.  The  latter  arrangement  gives  a  larger  storage-capacity  to 
the  bins  overhead,  but  this  advantage  is  obtained  at  the  greater 
cost  of  darkening  the  amalgamating-tables. 

The  mortar  is  the  most  interesting  feature  of  the  Homestake 
mills.  In  Prof.  Hofman's  paper  there  are  drawings  of  it,  one 
of  which  is  reproduced  here  in  Fig.  2.  Fig.  3,  from  a  photo- 
graph furnished  by  Fraser  and  Chalmers,  illustrates  the  latest 
design.  The  changes  in  the  dimensions  made  since  1888,  the 
date  of  Prof.  Hofman's  paper,  are  as  follows : 

1888.  1895. 

Weight,  .         .        ..         .  ;      .         .     5400  pounds.  7800  pounds. 

Length  of  base,       ....     54|  inches.  56|  inches. 

Width    "     "          .        „        .        .     27J-      "  28}      " 

Height,  .       ;.        ..        - .,      ,'       .     54£      "  58}      " 

Inside  width  at  the  level  of  the  lip,     13J      "  12 J      " 

The  most  important  change  is  the  narrowing  of  the  interior 
width  at  the  level  of  the  lip  of  the  mortar,  w^here  a  slight 
change  is  more  important  than  in  any  other  dimension.  The 
measurement  of  a  new  mortar  lying  outside  the  Golden  Star 
mill  gave  an  inside  width  of  13  inches.  At  the  Columbus  mill 
it  is  12  inches.  The  mortar,  as  now  made,  is  provided  with 
cast-steel  false  bottoms  2J  inches  thick,  with  a  cast-iron  lining 
|  inch  thick  along  the  sides  and  J  inch  thick  upon  the  feed- 
hopper.  The  inside  copper  plates,  placed  along  the  front,  are 
J  inch  .thick  and  are  attached  to  chuck-blocks.  The  latter  are 
wooden  blocks,  designed  so  as  to  serve  as  a  false  lip  to  the 
mortar,  thereby  raising  the  depth  of  the  issue.  A  piece  of  2- 
inch  plank  is  bolted  to  a  If-inch  board,  the  latter  being  made 
to  project  about  2  inches  beyond  the  former,  to  which  the  cop- 
per plate  is  attached.  The  2-inch  plank  had  been  replaced,  at 
the  time  of  Prof.  Hofman's  inspection,  with  J-inch  iron,  but 
has  since  been  reverted  to,  because  the  slight  increase  in  the 
distance  between  the  chuck-block  and  the  shoe  obtained  by  the 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       7 

arrangement  he  describes  was  undesirable  in  a  mortar  charac- 
teristically narrow  and  designed  for  rapid  crushing. 

Two  of  these  chuck-blocks  are  in  use,  one  9  and  the  other  7 
inches  high.  When  new  dies  have  been  introduced,  the  former 
is  inserted,  then  making  the  distance  from  the  bottom  of  the 
screen  to  the  top  of  the  die  about  9  inches.  As  the  dies  wear 
down,  the  depth  of  discharge  increases  until,  after  about  a 
fortnight,  it  becomes  necessary  to  replace  the  high  chuck-block 
with  the  lower  one.  The  difference  of  2  inches  between  the 
two  is  approximately  equal  to  the  diminution  in  the  thickness 
of  the  die.  After  a  further  service  of  two  or  three  weeks  the 
dies  are  worn  out,  the  depth  of  discharge  has  increased  to  11 
inches,  new  dies  are  inserted,  and  the  high  chuck-block  is  re- 
introduced.  In  this  way  some  sort  of  an  effort  is  made  to 
maintain  a  rough  uniformity  in  the  depth  of  the  issue,  a  factor 
the  importance  of  which  is  generally  overlooked  or  underesti- 
mated in  stamp-milling. 

It  may  be  added  that  the  copper  plate  on  the  high  chuck- 
block  is  flat,  while  on  the  other  it  has  a  curved  surface,  and  is 
mounted  on  slightly  thicker  wood,  so  as  to  bring  it  nearer  the 
die.  It  is  the  intention  of  the  mill-man  to  keep  the  bottom  of 
the  chuck-block  about  on  a  level  with  the  bottom  of  the  shoe, 
and  to  avoid  so  close  a  neighborhood  to  the  ore  on  the  die  as 
would  lead  to  the  scouring  of  the  amalgamated  surface  of  the 
copper  plate. 

There  is  only  one  inside  plate,  made  of  plain  copper  and  5 
inches  wide.  This  is  the  one  attached  to  the  chuck-block. 
There  is  no  back-plate,  as  was  the  case  in  the  Caledonia  mill 
(now  idle),  where  the  mortar  was  more  roomy  and  of  a  dif- 
ferent design.  Free  mercury  is  fed  at  intervals  into  the  bat- 
tery with  the  ore. 

The  Homestake  mortar  combines,  to  a  notable  degree,  the 
two  excellent  features  of  a  rapid  discharge  and  a  high  percent- 
age of  amalgamation.  Its  width  at  the  issue  used  to  be  13J, 
was  then  diminished  to  13,  and  in  the  newest  design  is  12 
inches.  The  depth,  by  the  introduction  of  chuck-blocks,  is 
raised  to  from  9  to  11  inches.  The  mortar  becomes  thereby 
both  narrower  and  deeper  than  the  Californian  pattern,  its  nar- 
rowness compelling  a  rapid  expulsion  of  the  pulp  and  giving 
the  mill  a  capacity  nearly  twice  that  of  the  average  Californian 


8      GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 


battery  when  working  ore  of  similar  character.  At  the  same 
time  the  depth  of  the  mortar  prevents  the  scouring  of  the  in- 
side plate,  and  permits  the  arrest  of  the  gold  by  this  plate  and 
by  the  free  mercury  added  with  the  ore,  so  that  the  percentage 
of  extraction  follows  closely  in  the  wake  of  the  roomy  mortar 
of  the  Colorado  mill,  the  crushing  capacity  of  which  is  only 
one-quarter  that  of  the  Homestake.  The  following  comparison 
will  be  of  interest : 

TABLE  II. — Comparison  of  Typical  Mills. 


. 

OT 

^. 

2? 

P. 

1 

p 

<u 

A 

1 

fi£ 

d, 

o.S 

1 

X 

\ 

a 

0 

DO 
O 

!l 

\ 

§Sg 

bj>S| 

.c 

S 

^W) 

|l 

I 

1? 

S 

Z- 

"S 

S 

Z3  O 

- 

£ 

(S 

f 

525 

w 

^P. 

Inches. 

Inches. 

Lbs. 

Inches. 

Tons. 

Golden  Star,  Dead  wood,  S.  Dak  

9  to  11 

850 

85 

4 

Hidden  Treasure,  Black  Hawk,  Col.. 

242 

13tol5 

550 

30 

17? 

1 

North  Star,  Grass  Valley,  Cal  

174 

4 

850 

84 

7 

\\ 

Pearl    Bendiffo    Australia 

1  Z 

15 

840 

74 

71 

*  4 

It  will  be  seen  how  closely  the  crushing-capacity  is  related 
to  the  interior  width  of  the  mortar  at  the  level  of  the  issue. 
Notwithstanding  its  rapid  crushing,  the  Homestake  mortar  re- 
tains a  percentage  of  the  total  gold  extracted  which  compares 
well  with  any  of  the  other  districts,  and  is  superior  to  some  of 
them,  though  this  factor  will  be  affected  by  the  variety  of 
screen  in  use. 

In  1888  the  Homestake  mills  were  using  ~No.  7  diagonal-slot 
Russia  iron  punched  screens.  At  the  present  time  the  mills 
uniformly  employ  the  No.  8  size  of  the  same  variety.  This 
means  slightly  finer  pulverization.  Prof.  Hofman  gives  the 
crushing-capacity  in  1888  at  4J  tons  per  stamp  per  day,  with  a 
9-inch  drop  85  times  per  minute.  It  is  now  about  4  tons  per 
day,  with  a  9J-inch  drop  and  the  same  speed.  This  shows  the 
effect  of  the  substitution  of  the  No.  8  for  the  No.  7  screen. 

The  No.  8  screens  are  considered  equivalent  to  30-mesh 
wire.  They  break  before  they  become  worn  out  because  of 
lines  of  weakness  developed  by  the  press  used  in  their  manu- 
facture. They  are,  however,  never  retained  in  service  until  the 


d 

c 

" 


FIG.  2. 


Scale,  1  inch  =  1  foot. 
The  Homestake  Mortar. 


FIG.  3. 


The  Homestake  Mortar. 


i 

m 


l *  1  r. 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

apertures  are  much  worn,  because  this  would  produce  a  coarse 
crushing  detrimental  to  a  uniform  product.  Their  maximum 
service  is  about  two  weeks,  but  this  is  rarely  attained,  because 
breakage  occurs  after  six  to  eight  days.  The  cause  of  this  is 
the  accumulation,  inside  the  battery,  of  wood  chips,  which  have 
found  their  way  into  the  ore  from  the  timbers  in  the  mine. 
They  tend  to  dam  up  the  pulp  within  the  mortar,  and  so  sub- 
ject the  screen  to  a  pressure  greater  than  it  can  bear.  This  re- 
sults in  a  break  or  a  burst.  Where  surface-ore  is  being  milled, 
as  at  the  Deadwood-Terra,  the  life  of  the  screen  is  prolonged 
to  an  average  of  nine  or  ten  days,  because  such  ore  comes  from 
•workings  where  there  is  but  little  timbering. 

At  the  neighboring  Columbus  mill,  30-mesh  brass  wire  is 
used,  and  the  choking  of  the  screens  is  minimized  by  having 
three  sets  for  each  battery,  so  that  while  one  is  in  place  the 
second  is  being  dried  out  and  the  third  cleaned  with  a  wire  brush. 
It  would  be  better  if  the  Homestake  mills  could  find  it  practi- 
cable to  use  wire-cloth  instead  of  punched  Russia  iron,  since, 
apart  from  the  advantage  of  a  more  uniform  discharge,  the  pul- 
verization is  more  regular,  because  the  wires  do  not  wear  so 
easily  as  the  punched  holes,  and  the  apertures  therefore  retain 
their  size,  and  the  screen  does  good  work  until  simple  breakage 
requires  that  it  be  patched  or  discarded. 

The  process  of  gold-extraction  consists  of  amalgamation 
within  the  mortar  upon  outside  plates  and  in  traps,  supple- 
mented in  a  rudimentary  way  by  an  inadequate  effort  to  con- 
centrate the  sulphides  of  the  tailings. 

The  mortar  becomes  an  amalgamating  apparatus  by  the  use 
of  the  inside  copper  plate  and  the  addition  of  free  mercury. 
About  50  per  cent,  of  the  total  amalgam  is  obtained  from  these 
inside  plates.  At  the  Deadwood-Terra  the  proportion  reaches 
70  per  cent. 

To  quote  from  my  previous  paper*  on  the  subject : 

' '  Mercury  is  fed  into  the  battery  in  quantities  proportioned  to  the  richness  of 
the  ore  and  regulated  by  the  condition  of  the  amalgam  on  the  apron-plates.  At 
the  four  principal  mills  the  rate  at  which  the  mercury  is  fed  can  be  judged  by  the 
accompanying  record,  coyering  the  two  weeks  preyious  to  my  yisit. 

"It  will  be  observed  that  though  the  Golden  Star  and  the  Deadwood-Terra 
mills  crush  approximately  the  same  amount  of  ore,  the  former  uses  more  than 

::  Eng.  and  Mining  Journal,  p.  222,  September  7,  1895. 


10       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 


twice  as  much  mercury.  This  fact  is  explained  by  the  wide  difference  in  the  rich- 
ness of  the  ore,  for  while  that  crushed  in  the  batteries  of  the  Golden  Star  aver- 
ages from  $4  to  $5  per  ton,  that  which  goes  through  the  Deadwood-Terra  ranges 
from  $1.50  to  $2  per  ton. 

TABLE  III. — Consumption  of  Mercury  at  the  Homestake 
Stamp-Mills. 


Date. 

Deadwood- 
Terra. 
160  Stamps. 

Golden  Star. 
160  Stamps. 

Highland. 
120  Stamps. 

Homestake. 
100  Stamps. 

Mayl,  1895  

Lbs. 
11 
10 
10 
12 
*  9 
10 
11 
11 
11 
10 
11 
10 

Ozs. 
5 
2 
0 
2 
12 
.     6 
11 
6 
8 
14 
0 
12 

Lbs. 
25 
*17 
25 
26 
25 
24 
23 
24 
23 
25 
23 
24 

Ozs. 
13 
14 
16 
13 
3 
8 
2 
12 
13 
3 
7 
6 

Lbs. 
15 
*12 
15 
17 
10 
16 
17 
19 
19 
18 
18 
17 

Ozs. 
4 
9 
1 
10 
6 
8 
0 
3 
8 
12 
8 
4 

Lbs. 
*  9 
12 
13 
12 
11 
12 
12 
12 
12 
12 
12 
11 

Ozs. 
10 

2 
0 
12 
7 
2 
8 
15 
13 
13 
7 
1 

2, 

3 

4 

5, 

6, 

7 

g' 

9 

'10 

11 

12 

Average  per  day  

11 

4 

24 

3 

17 

2 

12 

2 

"  For  the  year  ending  June  1,  1894,  the  Homestake  mill  used  2084  pounds  and 
the  Golden  Star  mill  3440  pounds,  making  a  total  of  5524  pounds  avoirdupois, 
which,  at  the  price  obtaining  that  year,  4*2  cents,  makes  the  value  of  the  mercury 
used  $2320.13.  During  that  time  309,210  tons  of  ore  were  crushed,  so  that  the 
consumption  was  at  the  rate  of  about  5  dwts.  Troy  or  |  cent  per  ton.  At  the 
DeadwoodrTerra  205  pounds  were  used  in  February,  1895,  in  treating  18,483 
tons  of  ore.  It  is  estimated  that  22  per  cent,  of  the  amount  of  mercury  used 
is  lost." 

On  issuing  from  the  battery  the  pulp  falls  from  6  to  10  inches 
before  striking  the  aprons  or  first  amalgamatiiig-tables.  This 
serves  no  particular  purpose,  while  the  actual  damage  possible 
to  the  plates  by  the  scouring  of  their  surface  due  to  the  impact 
of  the  pulp  is  obviated  by  the  interposition  of  a  splash-board, 
which  breaks  the  fall  of  the  sand  and  water.  This  splash-board 
might  be  placed  at  such  an  angle  as  would  permit  of  its  use 
as  an  amalgamating  device  by  lining  it  with  a  copper  plate. 

In  the  Homestake  Co.'s  mills  the  aprons  are  10  feet  in  length 
and  4J  feet  wide.  Those  in  the  Highland  mill  are  only  8  feet 
long.  In  all  these  mills  two  apron-plates  deliver  the  pulp  to 
one  tail-plate  having  a  size  equal  to  one  apron.  At  the  Dead- 

*  Indicates  clean-up  days. 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.        11 

wood-Terra  the  aprons  are  somewhat  larger,  namely,  11  feet  by 
4  feet  8  inches,  but  the  tail-plate  is  8  feet  long  and  only  16 
inches  wide.  The  latter  is  called,  very  appropriately,  a  sluice- 
plate,  and  is  a  truly  absurd  device  for  arresting  the  gold. 

In  the  Homestake  mills,  both  apron-  and  tail-plate  have  a 
slope  of  1 J  inches  per  foot,  the  minimum  gradient  at  which  the 
tables  can  clear  themselves  of  the  pulp.  Both  tail-plate  and 
apron  are  dressed  each  morning,  the  aprons  are  cleaned  up  par- 
tially each  day,  and  more  completely  deprived  of  their  amalgam 
at  the  bi-monthly  general  clean-up,  when  both  the  tail-plates 
and  the  inside  mortar  plates  are  gone  over. 

The  traps  are  intended  to  arrest  escaping  amalgam.  The 
Golden  Star  mill  (jsee  Fig.  4)  has  two  at  the  head  of  the  tail- 
plate.  They  are  18  inches  deep.  They  are  preceded  by  a 
shallow  trap  or  riffle  2  inches  deep,  which  is  stated  to  do  better 
work  because  of  the  more  regular  passage  of  the  pulp.  These 
traps  catch  about  1  per  cent,  of  the  total  amalgam.  They  are, 
to  quote  again, 

"  Cleaned  up  every  two  weeks,  the  accumulated  pyrites  are  shovelled  into  buckets 
and  then  passed  into  a  pan,  which  extracts  all  the  free  amalgam.  The  residues 
from  the  pan  are  then  fed  into  a  particular  5-stamp  battery,  provided  with  a  No. 
:0  slot  screen.  They  are  passed  through  this  battery  twice  and  are  then  sent  to 
the  smelter,  their  final  assay  value  being  about  $38  per  ton. 

"The  above  suggests  the  Australian  practice  of  mercury  Avells,  particularly  em- 
ployed at  Chines,  with  the  obvious  difference  that  the  Homestake  traps  are  not 
supplied  with  free  mercury.  It  is  claimed  that  if  sufficient  mercury  is  fed  into 
the  battery  no  free  gold  should  escape,  and  the  mercury  in  the  traps  would  merely 
serve  to  thin  the  amalgam  and  make  it  easier  of  escape.  The  traps  catch  concen- 
trates and  amalgam  only." 

Then  comes  the  concentration  of  the  sulphides.  Of  this, 
not  much  can  be  said.  The  Deadwood-Terra  mill  makes  no 
attempt  to  save  the  sulphides,  since  the  ore  comes  from  near 
the  surface  and  contains  nothing  worthy  of  supplementary 
treatment.  The  Homestake  mills  and  that  of  the  Highland 
company  are  using  the  Gilpin  county  bumping-table.  Seven 
years  ago  Prof.  Hofman,  noting  the  absence  of  any  effort  to 
save  the  valuable  sulphides,  suggested  the  employment  of 
Spitzhltten,  supplemented  by  Spitzkastev,  preparatory  to  the  re- 
crushing  of  the  coarse  sands  and  the  concentration,  on  buddies, 
of  the  fine.  This  very  sensible  advice  has  not  been  followed. 
Instead,  however,  two  blanket  houses  were  erected,  and,  with- 
out any  sizing  or  classification  such  as  should  precede  all  con- 


12       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

centration,  the  blanketings  were  worth  from  $20  to  $30,  per 
ton.  These  have  been  idle  for  several  years,  and  in  their 
place  eight  bumping-tables  were  placed  in  both  the  Highland 
and  Golden  Star  mills,  while  six  were  added  to  the  Homestake 
mill.  It  is  only  necessary  to  add  that  the  two  larger  mills  have 
crushing  capacities  of  560  and  640  tons  per  day.  and  the  Home- 
stake  about  400  tons,  to  indicate  the  absurdly  disproportionate 
nature  of  the  equipment,  which  can  only  be  considered  a  badly- 
designed  experiment.  The  results  obtained  are  not  by  any 
means  a  proof  .of  what  could  be  done  under  proper  conditions, 
as  already  stated  in  my  previous  criticism  of  this  feature : 

"During  the  year  ending  June  1,  1894,  the  two  Homestake  mills  produced 
915,010  pounds  of  concentrates  whose  assay  value  varied  »from  |5  to  $8  per  ton. 
They  consist  of  iron  pyrite,  arsenical  pyrite  and  pyrrhotite.  The  ore  contains 
from  3  to  5  per  cent,  of  sulphides,  but  only  about  2  per  cent,  are  saved.  They 
are  sent  by  rail  to  the  Deadwood  and  Delaware  Smelter,  just  below  the  town  of 
Deadwood,  where  they  are  treated  at  a  charge  of  half  their  assay  value,  and  con- 
verted into  an  iron  matte  very  low  in  copper  and  rich  in  gold,  which  goes  to 
the  Omaha  and  Grant  Smelting  and  Kefining  Company,  at  Omaha,  for  further 
treatment. ' ' 

At  the  present  time  experiments  are  being  made  with  jigs  in 
order  to  improve  this  part  of  the  milling.  It  is  to  be  regretted 
that  a  representative  company,  such  as  that  operating  the 
Homestake  mines,  should  be  so  slow  to  adopt  the  best  metal- 
lurgical practice,  remaining  satisfied  with  a  manifestly  inade- 
quate equipment  and  a  thoroughly  unscientific  treatment  until 
the  successful  work  of  a  Cornishman,  treating  its  mill  tail- 
ings a  few  miles  down  the  creek,  emphasized  the  desirability  of 
doing  something  better. 

Prof.  Hofman  has  described  in  detail  the  method  of  sampling 
the  mill-stuff  by  simple  panning.  At  the  present  time  the  mill- 
work  is  checked  by  sampling  the  pulp  as  it  leaves  the  apron- 
plates  and  fills  a  dipper  at  intervals  of  an  hour  for  a  period  of  five 
hours.  This  is  done  each  afternoon.  The  gold  is  determined 
by  fire-assay.  No  accurate  knowledge  of  the  completeness  of 
the  extraction  can  be  obtained  by  so  unsystematic  a  procedure. 

The  labor-costs  are  given  in  the  accompanying  table  : 

By  comparing  this  with  Table  V.  in  Prof.  Hofinan's  paper,  it 
will  be  noticed  that  the  mills  have  been  enlarged  without  a  pro- 
portionate increase  of  workmen.  In  1888  the  Homestake  mill 
employed  20  J  men  to  attend  to  80  stamps  and  the  Golden  Star 
23  J  men  for  its  120  stamps.  The  chief  change  is  hi  crusher- 


GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       13 


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14      GOLD-MILLING^IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 


men,  the  number  of  whom,  by  the  substitution  of  the  large  Gates 
for  the  small  Blake  rock-breakers,  has  been  diminished  from 
5  and  6  men  respectively  to  2  for  each  mill.  The  Golden  Star 
now  employs  4  general  laborers  in  place  of  2,  and  the  Home- 
stake  2  in  place  of  1,  and  this  is  the  only  increase  following  the 
enlargement  of  the  mill.  The  engine-men,  firemen,  amalgama- 
tors, etc.,  remain  the  same  in  number,  while  the  general  super- 
intendence (foreman)  has  been  diminished  for  any  single  mill 
by  giving  one  man  charge  of  both  the  Homestake  mills  as  well 
as  that  of  the  Highland  Co.'s. 

The  milling  costs,  per  ton  of  ore,  are  as  follows : 

TABLE  V.—Cost  of  Stamp-Milling  in  tfie  Black  Hills,  South  Dakota. 


A.—  THE  HOMESTAKE  MILL. 

Year  

1887-1888. 
80. 

1888-1889. 
80. 

1893-1894. 
80. 

Number  of  stamps 

Tons  treated 

96,790 

$0.2561 
0.0130 
0.1729 
0.2766 

106,780 

$0.2395 
0.0045 
0.1562 
0.2230 

104,995 

$0.2543 
0.0105 
Orl986 
0.0597 
0.1784 
0.1097 
0.0034 

Labor 

Supplies 

Water 

Wood 

Coal  

Machinery  

0.0922 
0.0109 
0.0016 
0.0103 
0.0070 

0.0893 
0.0084 
0.0014 
0.0053 
0.0139 

Oil  

Candles  

Quicksilver  

0.0083 
0.0167 
0.0155 

Lumber  

Timber  

Total  cost  per  ton  of  ore  

$0.8406 

$0.7415 

$0.8551 

B.—  THE  GOLDEN  STAB  MILL. 

Year  

1887-1888. 
120. 

1888-1889. 
120. 

1893-1894. 
160. 

Number  of  stamps 

Tons  treated 

146,565 

$0.2138 
0.0079 
0.1712 
0.2739 

161,755 

$0.1755 
0.0044 
0.1622 
0.1959 

204,215    , 

$0.1556 
0.0121 
0.2043 
0.0346 
0.1637 
0.1057 
0.0021 

Labor  

Supplies 

Water 

Wood       

Coal     

Machinery  

0.1220 
0.0084 
0.0014 
0.0252 
0.0054 

0.1088 
0.0066 
0.0014 
0.0082 

0.0088 

Candles  

Quicksilver 

0.0071 
0.0160 

Lumber  

Total  cost  per  ton  of  ore 

$0.8292 

$0.6718 

$0.7012 

GOLD-MILLINa   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       15 

Prof.  Hofmaii  gave  the  costs  for  the  year  ending  June, 
1888. 

It  is  remarkable  how  little  the  increased  crushing-capacity  of 
the  mills,  due  to  additional  stamps,  has  diminished  the  costs  per 
ton,  and  this  in  spite  of  the  general  cheapening  of  material  in- 
separable from  the  much  improved  communication  between 
Deadwood  and  the  centers  of  industry.  This  applies  especially 
to  the  Homestake  mill.  In  the  case  of  the  larger  plant  the 
diminution  of  12  cents  per  ton,  as  compared  with  1887-88,  did 
not  follow  the  addition  of  40  stamps,  since  previous  to  that  the 
cost  had  been  3  cents  less.  Much  of  this  discrepancy  is  trace- 
able to  the  fact  that  the  wood,  fuel,  water,  castings,  foundry- 
work,  etc.,  are  supplied  to  the  mill  by  subsidiary  companies. 

As  to  the  efficacy  and  completeness  of  the  mills  as  ore-reduc- 
tion plants,  I  find  myself  (always  excepting  the  feeble  attempt 
at  concentration)  to  be  very  favorably  impressed.  It  has  been 
urged  by  unfriendly  critics*  that  "  haste  and  waste  "  is  the  chief 
characteristic  of  the  milling-methods ;  but  this  has  been  said, 
I  venture  to  believe,  without  proper  regard  to  the  conditions  of 
the  case. 

Something  has  already  been  said,  in  the  early  part  of  this 
communication,  regarding  the  mode  of  occurrence  of  the  ore. 
The  immense  size  of  the  ore-bodies  and  the  extensive  nature  of 
the  mine  developments  justify  the  scale  of  the  Homestake  Co. 's 
operations.  The  ore  is  mixed  with  a  large  proportion  of 
country-rock — in  fact,  it  is  for  the  most  part  only  gold-bearing 
schist,  without  any  marked  boundary  or  any  very  noticeable 
difference  between  what  is  worth  exploitation  (and  consequently 
ore)  and  what  is  unprofitable  to  mine  (and  therefore  waste  or 
"  country  ").  Of  the  sulphides,  the  most  favorable  association  is 
that  of  arsenical  pyrites.  But  the  amount  of  sulphides  present 
is  small,  and  the  gold  is  not  very  closely  attached  to  them,  so 
that  the  ore  is  notably  "  free-milling."  In  fact,  in  my  opinion, 
it  is  more  docile  than  even  the  quartz  of  the  main  California!! 
gold-belt.  The  results  obtained  in  the  mills  confirm  this  view. 

However,  it  is  hard.  The  wear  and  tear  of  shoes  and  dies 
indicates  this.  The  shoes  wear  at  the  rate  of  from  36  to  37 


*  Kecently  by  Mr.  C.  G.  Wamford  Lock  in  "Gold  Mining  and  Milling  in  the 
Black  Hills,"  read  before  the  Institution  of  Mining  and  Metallurgy,  London, 
January  16,  1895. 


16       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

pounds  per  100  tons  of  ore,  and  the  dies  at  the  rate  of  44  to  48 
pounds.  This  represents  a  cost  of  only  about  2  cents  per  ton? 
at  the  prices  which  the  Homestake  Company  pays,  as  compared 
to  4  cents  at  Angels  Camp*  (California),  5J  cents  in  Gilpin 
county  (Colorado),  4J  cents  at  Bendigo  and  5J  at  Clunes  (in 
Australia),  9  cents  at  Grass  Valleyf  (California),  and  13  cents  at 
Mammoth,J  Final  county,  Arizona.  These  figures  are  instruct- 
ive, but  they  depend  largely  on  prices  and  freights.  The  follow- 
ing statement  of  wear  in  pounds  of  iron  per  100  tons  of  ore  is  a 
better  guide  :  At  Angels  Camp,  45  pounds  ;  Grass  Valley,  90 ; 
Gilpin  county,  58;  Bendigo,  144;  Clunes,  157;  Mammoth,  76; 
as  against  an  average  of  80J  pounds  at  the  Homestake.  The 
ore  of  Grass  Valley  is  very  hard  indeed,  while  the  lesser  hard- 
ness of  the  material  treated  by  the  Australian  mills  is  much 
more  than  offset  by  the  absence  of  rock-breakers.  The  ore  of 
Angels  Camp  and  Gilpin  county  is  comparatively  soft. 

At  present  the  Homestake  mills  save,  as  far  as  I  could  learn, 
somewhere  about  75  per  cent.  The  ore  is  low-grade.  During 
the  year  ending  June,  1894,  the  Homestake  and  Golden  Star 
mills  treated  309,210  tons,  yielding  f  1,390,610,  equivalent  to 
$4.49  per  ton.  Having  in  regard  the  low  tenor  of  the  ore,  the 
immense  reserves  of  it  and  the  evident  intention  not  to  work 
for  the  good  of  posterity,  it  seems,  from  a  commercial  stand- 
point, a  very  proper  thing  to  treat  it  with  the  utmost  dispatch 
and  rush  it  through  the  mills.  Of  course,  slower  treatment 
would  give  a  higher  extraction,  but  this  would  not  compensate 
for  the  greater  cost  per  ton  due  to  diminished  capacity.  More- 
over, the  results  are  not  bad;  75  per  cent,  is  an  extraction  above 
the  average  even  in  mills  treating  a  fraction  of  the  quantity 
crushed  per  stamp  in  this  district.  The  after-treatment,  the 
saving  of  the  sulphides,  is  a  serious  error,  and  the  arrangement 
of  the  plates§  is  a  blemish ;  but  the  excellence  of  the  design 
of  the  mortar,  the  ample  rock-breaker  capacity  and  the  general 
arrangement  of  the  mills  is  such  that,  taken  as  a  whole,  the 
milling  practice  is  one  of  the  best  examples  of  the  cheap  treat- 
ment of  a  large  mass  of  low-grade  ore. 


*  In  1891.  f  In  1892.  J  In  1893. 

%  Placing  one  tail-plate  below  two  aprons  having  a  combined  anialgamating- 
surface  twice  as  great  as  the  tail-plate. 


GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       17 

II. — GRASS  VALLEY. 

Mr.  Abadie,  in  his  excellent  description  of  the  work  at  the 
North  Star  mill,  did  not  concern  himself  with  the  methods  of 
his  neighbors  at  Grass  Valley.  This  was  doubtless  largely  due 
to  the  fact  that  the  mill  of  which  he  had  charge  was  generally 
acknowledged  as  representative  of  the  practice  of  the  dis- 
trict, 

The  following  additional  matter,  based  on  visits  to  this  dis- 
trict made  in  December,  1886,  May,  1891,  and  July,  1893, 
may,  however,  render  the  description  of  the  milling-practice 
more  complete. 

The  first  mill  erected  in  California  was  not  built  at  Grass 
Valley  in  1850,  as  stated*  by  Mr.  Abadie.  Mariposa  county 
claims  that  distinction,  and  accords  it  to  a  mill  of  8  stamps, 
each  in  its  own  separate  mortar,  erected  on  the  Mariposa  estate 
late  in  the  summer  of  1850.f  It  was  not  till  the  following  Jan- 
uary that  a  mill  was  erected  on  the  west  bank  of  Wolf  Creek, 
nearly  opposite  the  site  of  the  present  Empire  mill  at  Grass 
Valley. 

Mr.  Abadie's  drawings  and  photographs  very  completely  illus- 
trate the  position  and  interior  arrangement  of  the  North  Star 
mill.  The  drawings  are  particularly  valuable.  The  most 
notable  change  made  in  the  North  Star  mill  since  my  first  visit 
in  1886  has  been  the  new  arrangement  of  the  amalgamating- 
tables.  When  going  through  the  mill  for  the  first  time,  I  no- 
ticed the  inadequacy  of  the  amalgamating-surface  and  the  use- 
lessness  of  the  narrow  sluice-plates.  Since  then  the  shaking- 
tables  have  been  replaced,  in  the  case  of  the  last  two  batteries 
added  to  the  original  30  stamps,  by  new  wide  plates  which  are 
nearly  16  feet  long.  The  old  short  apron  and  narrow  sluice-plate 
have  been  thrown  out.  The  other  six  batteries  were,  at  the  time 
of  my  last  visit,  and,  it  would  appear, J  up  to  the  time  of  Mr. 
Abadie's  description  of  the  mill,  still  provided  with  the  primitive 
apparatus  which  was  first  criticized  by  me  nine  years  ago. 

This  is  the  great  blemish  of  the  North  Star  plant,  which  has 
followed  in  this  respect  the  design  of  the  typical  Californian 

*  Trans.,  xxiv.,  208. 

f  Information  derived  from  Mr.  Melville  Atwood  and  others  of  the  pio- 
neers. 

I  Page  215,  vol.  xxiv. 


18       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

mill,  whose  narrow  sluice-plates  are  a  remnant  of  the  appa- 
ratus originally  borrowed  by  the  quartz-miner  from  the  placer- 
digger. 

In  order  to  discuss  this  question,  a  detailed  description*  of 
the  passage  of  the  pulp  on  its  discharge  from  the  mortar  will  be 
necessary.  The  screen-frame,  which  is  4  feet  4  inches  long  and  18 
inches  wide,  has  four  partitions  dividing  the  issue  into  five 
portions.  Each  division  of  the  screen  surface  is  9  inches  wide 
and  12f  inches  high.  While  this  construction  strengthens  the 
screen,  it  robs  it  of  1  square  foot  of  discharging  area,  and  is  not 
therefore  to  be  commended. 

The  pulp  then  drops  six  inches  and  strikes  the  battery-plate, 
which  is  4  feet  2  inches  wide  and  18  inches  deep.  It  covers  an 
iron  apron  which  is  bolted  to  the  mortar. 

Then  there  succeeds  a  trough  from  which  the  pulp  passes 
through  a  distributor,  consisting  of  a  vertical  iron  partition 
pierced  by  20  {-inch  holes.  Then  follows  a  drop  of  3J  inches 
to  the  apron-plate.  The  latter  is  4  feet  5  inches  wide  f  for  2 \ 
feet,  and  then  becomes  narrowed  for  the  remaining  2  feet,  fin- 
ishing with  a  width  of  22  inches.  Then  come  the  sluice-plates, 
22  inches  wide  and  12  feet  long.  They  had  a  slope  of  1  inch 
per  foot  at  the  time  of  my  visit,  but  according  to  Mr.  Abadie, 
the  gradient  is  usually  greater,  viz.,  1  \  inches.  The  aprons  are 
given  1J  inches  per  foot. 

Then  come  the  copper-lined  shaking-tables.  The  new  plates 
are  16  feet  long,  of  which  the  upper  portion,  of  2J  feet,  is  53 
inches  wide  and  represents  the  former  apron,  and  the  remain- 
der is  46  inches  wide,  representing  an  enlargement  of  the 
sluices. 

Mr.  Abadie  says  that  these  new  plates  "  cannot  be  too  highly 
recommended,"  which  is  quite  true  when  we  contrast  them  with 
the  old  arrangement ;  but  one  may  be  permitted  to  ask,  Why 
this  narrowing  of  the  plate  from  53  to  46  inches  ?  I  take  the 
liberty  of  emphasizing  this  matter  because  it  has  for  many  years 
seemed  to  me  that  the  California  stamp-mill,  otherwise  the  best 

*  Much  of  which  appeared  in  my  article  on  "Grass  Valley,"  published  in 
the  issues  of  May  19  and  26,  and  June  2,  1894,  of  the  Engineering  and  Mining 
Journal,  New  York. 

t  Some  of  my  measurements,  obtained  by  actual  measurement  in  the  mill,  vary 
slightly  from  those  since  given  by  Mr.  Abadie. 


GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       19 

machine  of  its  kind  yet  evolved  by  the  ingenuity  of  man,  suf- 
fers seriously  from  an  unsuitable  arrangement  of  the  amalga- 
mating surface.  In  tracing  the  evolution  of  the  apparatus  of 
the  stamp-mill  it  will  be  found  that  the  first  gold-saving 
methods  were  modeled  after  placer-mining  practice,  and  that 
in  the  term  "  sluice-plate  "  lingers  the  evidence  of  the  transfer- 
ence of  the  sluice-box  from  the  gulch  into  the  mill.  The  ar- 
rangement of  4  feet  of  plate  as  wide  as  the  mortar,  followed 
by  10  or  12  feet  of  plate  somewhat  under  1  foot  wide,  was 
almost  universal  in  California  a  few  years  ago,  one  mill  copy- 
ing another  apparently  without  inquiring  into  the  object  of  the 
arrangement.  At  the  North  Star  an  examination  of  the  sluices 
showed  the  edges  of  copper  plate  to  be  abraded  or  scoured  by 
the  swift  passage  of  the  pulp. 

The  philosophy  of  the  sluice-plate  is  not  evident.  The  bat- 
tery and  apron  have  caught  the  coarser  gold — that  which  it  is 
easiest  to  arrest — and  the  object  is  to  prevent  the  escape  of 
particles  which,  because  they  were  fine  and  difficult  to  catch, 
have  not  been  stopped.  Hence,  the  sluice-plate  is  put  in,  but 
it  is  more  a  launder  for  the  convenient  conveyance  of  the 
pulp  to  the  vanners  than  a  gold-saving  device.  How  can  we 
expect  to  catch  gold  which  could  not  be  arrested  on  a  wide 
plate,  by  passing  it  over  a  very  narrow  one  ?  The  quantity 
of  water  and  crushed  ore  is  still  the  same,  but  it  is  crowded 
into  a  much  lessened  space,  the  speed  of  its  passage  is  in- 
creased, and  the  depth  of  its  flow  augmented.  In  some  mills 
the  grade  of  the  sluice-plate  is  actually  greater  than  that  of  the 
apron. 

Therefore  the  ordinary  practice  should  be  reversed,  the  apron 
should  be  succeeded  by  a  wider  rather  than  a  narrower  plate, 
additional  facilities  for  the  catching  of  the  gold  should  be 
given  by  spreading  the  pulp  so  that  every  opportunity  is  af- 
forded for  its  contact  with  the  amalgamated  surface  of  the 
plate. 

The  necessity  for  a  uniform  depth  of  battery  discharge  is 
hardly  appreciated  at  Grass  Valley.  At  the  North  Star  no 
serious  attempt  was  made  to  regulate  it,  so  that  it  used  to  vary 
from  2  to  6  inches.  Since  my  last  visit  it  has  become  the  prac- 
tice to  introduce  cast-iron  plates  2  inches  thick  underneath  the 
dies.  They  have  lessened  the  difference  between  the  minimum 


20       GOLD-MILLING   IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

and  maximum  depths  of  discharge,  according  to  Mr.  Abadie,* 
to  2  inches.  Although  his  account  does  not  state  the  fact,  yet 
the  context  would  indicate  that  these  plates  are  introduced  after 
the  dies  have  been  worn  down,  thereby  restoring  the  height  of 
the  issue.  At  the  Empire  old  dies  used  to  be  placed  under- 
neath as  the  dies  in  use  were  worn  down,  and  this  was  found 
preferable  to  employing  iron  plates  for  false  bottoms  (as  at  the 
North  Star),  because  the  latter  broke  so  often.  If  they  are 
made  to  fit  snugly,  this  breakage  should  be  no  great  detri- 
ment, as  the  pieces  will  remain  in  place.  In  addition  to  these 
methods,  the  Empire  mill  uses  the  device  of  fixing  wooden 
cleats  to  the  bottom  of  the  screen  outside.  The  sand  banks 
up  inside  the  mortar,  and  protects  the  unused  strip  of  screen 
until  such  time  as,  the  dies  having  worn  down,  the  cleats  are 
removed  and  the  issue  lowered.  At  another  mill,  the  W.  Y.  O.  D. 
("  Work  Your  Own  Diggings  "),  the  dies  are  discarded  before 
they  have  worn  down  deeply.  The  remnant  is  sold  to  the 
local  foundry,  and  helps  to  pay  for  new  dies.  This  is  wise. 
The  consumption  of  a  few  pounds  of  iron  is  a  very  small  ma1> 
ter  compared  to  the  importance  of  maintaining  the  conditions 
best  adapted  to  good  work.  When  the  depth  of  discharge 
varies  between  wide  limits,  the  operation  of  the  mill  must  be 
irregular.  The  minimum  and  the  maximum  depths  cannot  be 
equally  favorable  to  the  particular  conditions  required,  and  an 
effort  should  be  made  to  find  the  exact  depth  best  adapted  to 
the  treatment  of  the  ores  of  the  special  mine,  and  that  figure 
should  then  be  maintained  as  far  as  is  practicable. 

In  the  matter  of  screens,  the  Grass  Valley  mills  have,  as  it 
seems  to  me,  taken  a  retrograde  step.  The  general  adoption 
of  punched  tin-plate  in  place  of  wire-cloth  is  defended  on  the 
ground  of  economy,  Thus,  Mr.  Abadie  says  that  "  the  life  of 
a  tin  screen  is  about  30  days;  the  cost,  one-fourth  that  of  wire 
screens."  As  a  rule,  at  Grass  Valley,  the  brass-wire  screens 
cost  $1.55  apiece,  while  the  tin-plate  costs  55  cents  per  screen, 
the  former  giving  a  service  of  25  days,  the  latter  of  14  to  15 
days.  Steel-wire  cloth  was  discarded  because  that  which  was 
used  in  this  district  had  the  defect  of  a  shifting  of  the  horizon- 
tal wires.  The  introduction  of  tin-plate  into  the  California!! 

*  Trans.,  vol.  xxiv.,  p.  212. 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       21 

mills  dates  several  years  back.  I  first  saw  it  in  use  at  the 
Utica  mill,  Angel's  Camp,  in  1886.  In  1893  the  Idaho  was 
the  only  mill  in  Grass  Valley  which  was  not  employing  tin- 
plate  in  preference  to  wire-cloth.  It  is  the  usual  custom  to 
burn  off  the  tin  upon  the  blacksmith's  forge,  with  the  idea 
that  the  iron  plate  becomes  annealed  and  toughened.  Since 
tin  amalgamates,  its  removal  prevents  the  adherence  of  mer- 
cury to  the  screens. 

The  cost  of  screens  per  ton  of  ore  varies  from  j  to  1  cent  per 
ton,  an  item  of  expense  which  is  trifling  when  compared  to 
the  importance  of  getting  a  screen  which  will  properly  size  the 
pulp  and  aid  in  maintaining  the  conditions  most  favorable  to 
good  amalgamation.  As  between  punched  tin-plate  and  wire- 
cloth,  the  advantage  in  cheapness  possessed  by  the  former  need 
not  be  considered  unless  it  accompanies  other  more  serious  ad- 
vantages ;  the  difference  of  half  a  cent  this  way  or  that  is  as 
nothing  when  measured  against  good  milling. 

No  one  at  Grass  Valley  had,  as  far  as  I  could  learn,  made  any 
careful  experiments  to  determine  the  action  upon  the  pulp  of 
the  use  of  the  two  varieties  of  screen.  One  would  naturally 
expect*  a  more  free  issue  and  a  more  uniform  crushing  when 
using  wire-cloth  in  place  of  punched  plate, f  because  the  former 
has  a  discharge-area  approximately  one-half  of  its  surface, J 
while  the  latter,  having  apertures  of  the  same  size,  has  •  less  of 
them  per  square  inch.§ 

In  making  such  tests  it  is  necessary  to  be  particularly  careful, 
not  only  that  the- same  kind  of  ore  is  fed  and  that  the  mortars 
are  the  same,  but  also  that  the  shoes  and  dies  are  in  the  same 
state  of  wear,  so  that  the  depth  of  discharge  is  equal  in  both 
batteries.  Moreover,  attention  should  be  paid  to  the  possibility 


*  The  only  results  of  experiment  published  are  those  contributed  by  Mr.  Thos. 
H.  Leggett  to  the  Eng.  and  Mining  Journal  of  June  30,  1894,  where  it  is  shown 
that  as  between  a  round  punched  tin,  No.  0  screen  and  a  40-mesh  steel  cloth,  the 
former  made  nearly  11  per  cent,  less  fines  (passing  through  a  100-mesh  screen) 
than  the  latter. 

f  A  recent  test  at  the  Mammoth  mill,  Final  county,  Arizona,  showed  that  as 
between  a  No.  6  slot-screen  and  an  equivalent  wire  cloth,  24-mesh  and  26  B.  W. 
G.  wire,  the  latter  crushed  20  per  cent,  more  than  the  former. 

J  With  a  width  of  mesh  .027,  a  thickness  of  wire  .01,  and  a  gauge  (B.  W.  G.) 
of  33,  the  discharge-area  is  just  one-half  the  total  surface. 
'  %  See  also  Trans.,  xxiii.,  563. 


22       GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY. 

of  more  fine  stuff  finding  its  way  into  one  mortar  than  into  the 
other.  The  outer  hatteries  of  a  stamp-mill,  where  the  rock- 
hreaker  is  in  the  center,  receive  more  than  their  share  of  the 
fines. 

The  milling-practice  of  the  Grass  Valley  district  has  under- 
gone important  changes  during  the  past  ten  years.  The  intro- 
duction of  an  inside  amalgamating-plate — first  done  at  the 
North  Star  in  1888 — marked  an  important  departure  from  the 
extreme  type  of  fast-crushing  California  battery.  The  tendency 
to  increase  the  percentage  of  inside  amalgamation  hy  deepening 
the  discharge  and  inserting  a  chuck-block  (which  also  carries  an 
amalgamating-plate)  is  a  notable  feature.  Thus  from  a  rapid 
pulverizer  the  California  mill  has  been  made  an  improved 
amalgamator.  This  older,  very  shallow-drop  mill,  unable  to 
use  a  plate  inside  the  mortar,  and  relying  solely  on  the  outside 
tables,  has  become  rare  on  the  Pacific  slope.  It  has  become 
a  recognized  fact  that  rapid  crushing  will  not  compensate  for 
poor  amalgamation;  that  the  sooner  we  catch  our  gold  the 
better ;  and  that  the  best  feature  of  the  stamp-mill,  as  compared 
to  other  pulverizers,  is  its  capability  to  combine  the  crushing 
and  amalgamating  apparatus  in  one  machine. 

At  the  North  Star  and  W.  Y.  0.  D.  mills  nearly  twice  as 
much  amalgam  is  obtained  from  the  inside  as  from  the  outside 
of  the  -mortar ;  while  at  the  Empire  the  inside  extraction  is 
from  50  to  85  per  cent,  of  the  total  saving. 

Heavy  silver-plating  is  recommended  nowadays.  The  North 
Star  plates  carry  1  ounce  of  silver  per  square  foot,  those  of 
the  Empire  have  2J  ounces,  while  at  the  W.  Y.  O.  D.,  the  newest 
plant,  the  amount  has  been  increased  to  5  ounces.  One  cannot 
remember  too  often  that  it  is  amalgam  that  catches  gold,  and 
that  a  good  coating  of  gold-amalgam  is  better  than  all  the  nos- 
trums in  creation.  In  starting  a  new  mill  or  introducing  new 
plates  a  good  coating  of  silver  helps  to  get  the  tables  into  work- 
ing order  in  a  short  time,  the  silver  being  gradually  replaced  by 
gold.  There  is  no  economy  in  poorly-plated  tables  or  in  short, 
narrow  ones.  No  mill  I  have  ever  seen  had  too  mucji  amal- 
gamating-surface ;  many  of  them  have  had  too  little.  The 
value  absorbed  by  the  plates  is  an  asset  of  the  best  kind;  and 
there  is  no  plate  placed  in  a  mill  but  will  absorb  some  gold  and 
be  worth  more  when  it  is  worn  out  and  discarded  than  wheli 


GOLD-MILLING    IN    THE    BLACK    HILLS    AND    AT    GRASS    VALLEY.       23 

it  was  first  put  in  place.  The  following  fact*  will  be  of  interest 
in  this  connection.  The  old  plates  of  the  60  stamp-mill  of  the 
Montana  Co.,  Ltd.,  at  Marysville,  Montana,  after  4J  years' 
steady  work,  1887-1891,  were  scraped  and  melted  down.  (This 
was,  of  course,  after  they  had  undergone  the  usual  periodical 
clean-up.)  The  12  plates,  each  54  by  96  inches,  yielded  $90,- 
000.  One  plate  gave  as  much  as  $8000.  Even  the  small  vanner 
plates, f  16  by  48  inches,  yielded  $500  each. 

The  importance  of  the  careful  sampling  of  the  tailings  as  a 
check  upon  the  mill-work  is  better  appreciated  at  Grass  Valley 
than  in  any  other  locality  I  have  visited.  At  the  Empire  mill 
there  is  an  automatic  sampler,  invented  by  Mr.  Starr,  the  former 
superintendent,  which  does  excellent  service.  The  results  in- 
dicate a  saving  of  from  85  to  87  per  cent.,  which  is  fairly  repre- 
sentative of  the  district. 


*  Which  I  owe  to  Mr.   B.  T.  Bayliss,  the  general  manager  of  the  Montana 
Co.,  Ltd. 

f  In  the  neighboring  50-stamp  mill. 


SUBJECT  TO 


[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Veins  of  Boulder  and  Kalgoorlie. 

BY   T.    A.    RICKARD,    DENVER. 
(New  Haven  Meeting,  October,  1902.) 

COMPARISONS  frequently  do  good  service  by  affording  a 
means  of  distinguishing  the  features  which  are  essential  from 
those  which  are  merely  accidental.  When  one  reads  of  the 
lode-structure  of  a  new,  and  perhaps  distant,  gold-field,  there 
arises  the  desire  to  compare  the  characteristics  mentioned  with 
those  of  the  regions  with  which  one  is  already  familiar.  It 
will  therefore  be  interesting  to  refer  to  the  other  districts  with 
which  Cripple  Creek  has  been  likened. 

A.  THE  VEINS  or  BOULDER  COUNTY,  COLORADO. 

Telluride-ores  have  been  mined  in  Colorado  since  1872. 
Previous  to  1891,  when  Cripple  Creek  was  discovered,  the 
principal  localities  for  such  ores  were  the  La  Plata  mountains 
and  Boulder  county.  The  former  district  is  situated  in  the 
extreme  southwestern  part  of  the  State.  Boulder  is  about  90 
miles  due  north  of  Cripple  Creek,  in  that  part  of  Colorado 
which  was  first  opened  up  by  the  pioneers  of  1859.  The 
prevailing  rock  is  the  granite-gneiss  of  the  Front  range.  The 
veins  are  notably  associated  with  bands  of  chloride  gneiss,  to 
which  the  French  geological  term  of  "  protogine  "  was  formerly 
applied.  Dikes  of  quartz-porphyry  and  quartz-andesite  occur 
at  frequent  intervals.  In  this  respect  Boulder  resembles  the 
adjacent  well-known  district  of  Gilpin  county,  but  the  ore- 
occurrence  does  not  appear  to  be  as  intimately  connected  with 
the  dikes  as  it  undoubtedly  is  in  Gilpin. 

The  veins  of  Boulder  appear  to  be  bands  of  crushed  rock 
accompanying  lines  of  fracture  which  have  been  healed  by  the 
impregnation  of  ore.  Fig.  1  will  illustrate  this  characteristic 
type.  The  Enterprise  is  the  principal  lode  of  the  El  Dora  dis- 
trict, 011  the  western  border  of  the  county.  The  enclosing 
formation  is  granitoid-gneiss,  traversed  by  belts  of  protogine 


2  THE    VEINS    OF    BOULDER    AND    KALGOORLIE, 

and  mica  schist.  In  this  instance  a  band,  8  inches  thick,  of  clay, 
called  "  gouge  "  by  the  miners,  and  consisting  of  rock  crushed 
to  the  condition  of  mud,  follows  the  hanging-wall,  which  ap- 
pears as  a  distinct  parting,  separating  the  lode,  A  C,  B  D,  from 
the  enclosing  country-rock.  Next  to  the  "  gouge  "  comes  a  well- 
defined  strip,  3  to  4  inches  wide,  of  casing,  which  is  made  up  of 
brecciated  gneiss  so  laminated  as  to  resemble  a  shale.  The 
foot-wall  is  not  very  distinct,  because  the  lode-matter  merges 
insensibly  into  the  country-rock.  The  ore,  Gr  H,  appears  in  the 
form  of  dark  threads  of  flinty  quartz  arranged  in  parallel  lines 
amid  the  lode-stuff,  which  is  essentially  a  granular  matrix  of 
partially-crushed  granite-gneiss.  The  dark  quartz  carries 
finely-disseminated  tellurides,  chiefly  petzite,  which  renders  a 
width  of  2  to  2J  feet  sufficiently  rich  to  yield  an  average  of  2 
ounces  of  gold  per  ton. 

The  Monongahela  vein,  shown  in  Fig.  2,  occurs  at  Sunshine, 
in  the  central  part  of  Boulder  county,  and  resembles  a  score  of 
similar  lodes  to  be  seen  in  the  small  mines  which  yield  the  bulk 
of  gold  from  this  interesting  region,  and  are  intermittently 
worked  under  lease  by  parties  of  experienced  miners.  Fig.  2 
represents  the  eastern  face  of  the  100-ft.  level  in  the  Monon- 
gahela workings  as  seen  in  April,  1897.  The  most  prominent 
feature  of  the  section  is  a  dark  band  (A  E,  C  H)  of  "  horn- 
stone,"  or  flinty  quartz,  which,  on  closer  examination,  is  found 
to  be  composed  of  two  separate  streaks,  A  F-C  G-  and  F  E-G 
H,  in  both  of  which  specks  of  petzite  are  clearly  distinguish- 
able. The  upper  portion,  3.  inches  wide,  has  numerous  cavities, 
"  vughs,"  lined  with  crystalline  quartz  and  marcasite  (white 
iron  pyrites).  The  lower  one,  2J  inches  wide,  is  more  com- 
pact. Between  the  pay-streak  (A  E,  C  H)  and  the  foot-wall 
(B  D)  there  is  a  thickness  of  7  inches  of  dark-gray  quartz, 
through  which  patches  and  streaks  of  granular  protogine  are 
distributed.  This  band  carries  only  traces  of  gold.  It  marks 
the  transition  between  ore  and  country-rock.  There  is  no  dis- 
tinct hanging-wall.  A  narrow  width  of  crushed  country,  A  C, 
separates  the  pay-streak  from  the  enclosing  rock.  The  latter  is 
traversed  by  several  dark  threads  of  flinty  quartz,  which  may 
be  regarded  as  feeders  to  the  vein  proper. 

A  little  further  west  the  pay-streak  splits  into  two  dark  fila- 
ments of  hornstone,  separated  by  mottled  quartz,  and  the  lode 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE. 

E 


Granitoid  Gneiss 


Clay 


Quartz 


Casing 


•  N.i  //(Crushed  Rock 


ENTERPRISE  VEIN.  EL  DORA,  COLO. 


4  THE    VEINS    OF    BOULDER    AND    KALGOORLIE. 

becomes  more  valuable.  This  change  is  illustrated  in  Fig.  3. 
The  band  (E  B,  H  D,  in  Fig.  2)  of  quartz  containing  inclusions 
of  country-rock  has  thinned  out,  and  finally  disappeared.  The 
double  streak  of  ore  (A  F-C  G  and  F  E-G  H  in  Fig.  2)  has 
separated  into  two  threads  (E  K  and  F  L  in  Fig.  3)  of  banded 
hornstone,  containing  frequent  cavities  lined  with  quartz-crys- 
tals. Between  these  two  threads  there  is  a  width  of  5  inches  of 
dark  mottled  hornstone,  containing  tellurides,  and  forming, 
therefore,  rich  ore.  The  small  thickness,  A  C,  of  altered 
country  to  be  seen  on  the  hanging-wall  side  in  Fig.  2  has  be- 
come amplified  in  Fig.  3  to  a  3-inch  casing,  C  G,  of  crushed 
rock,  and  a  further  width,  D  H,  of  6  inches  of  breccia,  con- 
sisting of  fragments  of  protogine  cemented  by  brown  quartz. 
The  lode,  which  may  be  considered  as  extending  from 
C  to  F  and  from  G  to  L,  is  in  protogine,  and  consists  of  that 
rock  in  variously  altered  condition,  graduating  from  crushed 
country-rock,  C  G,  to  crushed  rock  impregnated  with  quartz, 
D  H,  and  finally  into  a  clean,  dark,  siliceous  matrix,  E  F,  K  L, 
to  which  the  term  "  hornstone  "*  can  be  fitly  applied.  The 
nature  of  the  ore-occurrence  can  be  further  inferred  from  the 
gold-contents  of  the  various  portions  of  the  lode.  Thus,  C  G 
was  poor,  that  is,  it  contained  ^  of  an  ounce  or  so  of  gold  per 
ton;  H  D  carried  8  ounces  of  gold  per  ton;  and  the  main 
streak,  E  F,  K  L,  was  worth,  at  the  time  of  my  visit,  from  $2.50 
to  $5  per  pound.  The  band  H  D  becomes  at  times  so  impreg- 
nated with  dark  quartz  as  to  merge  into  the  main  streak  of 
ore. 

There  is  no  selvage  separating  the  ore-streak,  E  F,  K  L, 
from  the  enclosing  rock.  The  seam  of  black  hornstone, 
F  L,  is  "  frozen "  to  the  foot-wall.  This  "  hornstone "  is  a 
characteristic  feature  of  the  telluride-bearing  streaks  of  Boulder 
county.  It  is  essentially  massive,  compact  silica,  otherwise 
chalcedony  or  flinty  quartz,  darkened  by  the  presence  of  finely 
disseminated  particles  of  iron  pyrites  (chiefly  marcasite)  and  the 


*  The  miners,  by  evident  confusion,  called  the  dark,  flinty  veinstone  "  horn- 
blende," instead  of  "  hornstone,"  and  in  the  same  manner  they  had  converted 
"  vugh-hole"  into  "bug-hole."  Hornstone  is  good  Anglo-Saxon,  horn  meaning 
resembling  horn  in  being  callous  or  hard,  as  in  "horny-handed  son  of  toil." 
The  word  "  chert  "  is  nearly  a  mineralogical  equivalent  for  hornstone.  Chert  is 
Irish,  and  originally  meant  "  pebble." 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE. 
FIG.  2  A   F   E 


~"~          '"  '' 


1-  '      '       ''   l''11 


P^4\\W>~'~<~'~' "V  '-•  --•  v-'-' 
Ml\j--\\W'V'-,  "\-r  -,.  •  ,  •  , 

''V''Vr  r--,  --*  sp  - "'"  ^'J1:.:':':1  A' :•:':•:' jj 

^'V-'-lvVV^vffll^H^ 

'^'':'r^-^ 


CT/  I          — •          _-.-.'_      —  —      -_    —   - 

III/'    l      '       '        '''_'''       'j      '-'      'j 

vv"  "  "r.  'V'~   r,  r.  ' 


Hornstone 


Quartz 


MONONGAHELA  VEIN,  BOULDER  COLO. 


6          THE  VEINS  OF  BOULDER  AND  KALGOORLIE, 

tellurides  of  gold  and  silver  (either  petzite  or  sylvanite).  The 
richer  portions  are  frequently  characterized  by  the  presence  of 
prochlorite  and  roscoelite.  The  latter,  which  is  a  vanadium- 
mica,  of  a  brownish-green  color,  is  so  notably  associated  with 
the  valuable  ores  of  Boulder  that  the  miners  have  got  into  the 
way  of  considering  it  an  essentially  gold-bearing  mineral.  It 
occurs  in  the  lodes  of  Kalgoorlie,  in  West  Australia,  and  quite 
recently  it  has  been  found  in  the  "  Last  Dollar,"  "  Mary 
McKinney,"  and  other  mines  in  the  Cripple  Creek  district.* 

B.    THE  LODES  OF  KALGOORLIE,  WEST  AUSTRALIA. 

Kalgoorlie  shares  with  Cripple  Creek  the  honor  of  having 
brought  tellurides  to  the  front  rank  among  the  ores  from  which 
gold  is  won.  The  two  districts  have  been  likened,  but  erro- 
neously. Their  geological  unlikeness  is  their  most  interest- 
ing feature. 

The  veins  occur  in  chloritic  schist,  the  vein-stuff  being  essen- 
tially the  same  as  the  encasing  country-rock,  but  more  schistose 
in  structure  and  more  calcareous  in  composition.  There  has 
been  much  discussion  among  petrographers  concerning  the 
original  character  of  the  country  enclosing  the  veins.f  The 
alteration  in  the  rock  induced  by  extreme  metamorphism  has 
rendered  the  conclusions  of  observers  anything  but  unanimous. 
In  the  district  itself  the  term  "  diorite  "  is  loosely  employed 
by  the  mine-managers  to  describe  the  prevailing  formation,  but 
microscopic  sections  exhibit  a  good  deal  of  quartz  and  no  horn- 
blende, and  therefore  prove  that  term  to  be  inappropriate. 
Some  feldspar  can  be  detected.  Titaniferous  iron  and  mica  are 
present.  From  sections  which  I  secured  in  1897  Prof.  Judd, 
F.R.S.,  concluded  that  the  prevailing  rock  was  a  highly  altered 
quartz-andesite.  As  the  formation  appears  underground  it  is 
a  fine-grained  foliated  rock  or  schist  with  a  silvery-green  sheen 
and  a  fissile  structure.  It  is  rendered  tough,  and  also  soft,  by 


*  See  "The  Telluride  Ores  of  Cripple  Creek  and  Kalgoorlie,"  Trans.,  vol. 
xxx.,  pp.  708-718.  Fine  specimens  of  roscoelite  have  been  lately  obtained  from 
the  Logan  mine,  near  Crisman,  in  Boulder  county.  Roscoelite  is  named  after  Sir 
Henry  E.  Roscoe,  the  celebrated  chemist. 

f  Most  of  the  evidence  on  this  mooted  point  is  well  summarized  by  Mr.  George 
W.  Card,  in  vol.  vi.,  part  i.,  "Records  of  the  Geological  Survey  of  New  South 
Wales,"  1898. 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE. 

C  E          F 


I        '        ' v  I 


r  "r    -~  i   .  ' 


,  I  \  -'-,    /\/       V 

~-—        i""        IN'XX'  ' 


'"  > 


, 

- 


' 


j  '  '_-/'_  -U  -'-^  V-< 


jHornstone  /Vugn 

MONONGAHELAVEIN,  NO.  2 


8 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE. 


reason  of  the  calcite  and  sericite  (or  hydrous  mica)  which  it 
carries. 

A  typical  lode  is  illustrated  in  Fig.  4,  which  shows  the  face 
of  the  270-ft.  level  in  the  Great  Boulder  Main  Reef  mine,  on 
Oct.  18,  1897.  It  is  a  schistose  band  of  rock  with  a  well- 

FIG.  4 


p     TAR   1807 

(4  Quartz  and  Calcite 

A  K'ALGOORLIE  LODE 

defined  line  of  parting,  A  F.  This  "  east  wall,"  as  it  is  termed, 
forms  one  boundary  of  the  gold-bearing  rock,  that  is,  the  lode, 
which  has  no  denned  limit  on  the  west,  but  graduates  into  the 
country-rock  on  that  side.  There  is  an  evident  struggle  between 
two  systems  of  fracture ;  the  rock  which  is  ore-bearing,  A  C, 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE.  9 

D  F,  is  sheeted  along  lines  which  are  nearly  upright  and  paral- 
lel to  the  parting,  A  F,  while  the  surrounding  country  has  a 
contrary  cleavage.  The  ore  differs  further  from  the  surround- 
ing rock  in  being  traversed  hy  veinlets  of  calcite  and  granules 
of  quartz  arranged  along  the  lines  of  fracture.  Iron  pyrites  is 
also  liberally  scattered  through  this  calcareous  vein-stuff. 
Petzite  and  calaverite  gave  the  lode  here  illustrated  an  average 
value  of  3 \  ounces  of  gold  per  ton. 

The  telluride-ores  of  Kalgoorlie  appear  sometimes  to  occur 
in  long,  overlapping  lenses,  as  is  illustrated  in  Fig.  5,  which 
represents  a  series  of  ore-bodies  cut  at  the  third  level  of  the 
Lake  View  Consols  mine.  It  is  said  that  the  original  owners 
of  this  now  famous  property  followed  the  line  of  one  of  these 
long,  torpedo-like  lenses,  and,  not  knowing  the  nature  of  the 
occurrence,  their  workings  ran  out  into  barren  country  so  as  to 
necessitate  a  cross-cut,  which,  unfortunately,  was  put  out  on  the 
wrong  side,  with  the  final  result  that  they  concluded,  as  the 
Cornishman  would  say,  u  that  the  lode  had  just  naturally 
petered  out."  The  ore  tends  to  spread  from  one  plane  of  folia- 
tion in  the  schist  to  the  next  one  on  the  right,  with  the  result 
that  the  longer  axis  of  each  lens  makes  a  small  angle  with  the 
strike  of  the  country,  and  the  successive  lenses  follow  one 
another  en  echelon.*  An  occasional  "  wall"  may  be  prominent 
and  the  ore  may  follow  it  for  a  short  distance,  but  it  will  leave 
it  for  another,  equally  well-marked.  The  "  walls  "  or  planes  of 
parting  do  not  limit  the  ore-channel ;  some  of  them  are  within 
it,  some  extend  beyond  it,  to  become  faint  as  they  are  followed 
into  the  surrounding  country.  In  the  space  separating  the 
lenses  there  are  stringers  and  small  seams  of  ore  which  serve 
as  connecting  threads  of  discovery.  They  act  as  "leaders,"t 
guiding  the  observant  miner  from  one  ore-body  to  another. 

The  description  of  veins  in  two  districts  so  far  apart  on  the 
map  as  Boulder  in  Colorado  and  Kalgoorlie  in  West  Australia 
emphasizes  the  diversity  of  structure  characteristic  of  the  lodes 
which  carry  gold.  Both  types  of  veins  occupy  fractures  which 


*  A  military  term  descriptive  of  the  movement  of  troops  advancing  in  diagonal 
step-like  succession. 

t  This  is  an  Australian  term  which  is  worthy  of  adoption.  Leader  is  from  the 
A.  S.  Iredan,  to  guide,  just  as  lode  is  from  lad,  a  path.  A  lode  is  the  occurrence 
of  ore  which  guides  or  leads  a  miner. 


10 


THE  VEINS  OF  BOULDER  AND  KALGOORLIE. 


X          Ol 


X         X| 


X 


I  X    x  X       X 

X 


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THE  VEINS  OF  BOULDER  AND  KALGOORLIE.         11 

have  been  healed  by  mineral  solutions ;  the  Boulder  type  is  dis- 
tinctly a  segregation  of  amorphous  quartz  in  the  form  of  flint, 
with  a  cementing  of  the  adjacent  granite,  which  had  been 
brecciated  at  the  time  of  the  formation  of  the  vein  fracture ; 
the  Kalgoorlie  type  represents  a  sheeting  of  the  schistose  coun- 
try without  any  clean-cut  fissuring  and  without  a  brecciation 
of  the  country,  which,  being  more  tough  than  a  granular  rock, 
such  as  granite,  and  less  fissile,  exhibits  the  effects  of  strain  in 
a  system  of  parallel  sympathetic  partings,  along  which  calcite 
and  quartz  have  been  deposited,  and,  with  them,  the  tellurides 
of  gold.  In  the  Boulder  type  the  tendency  is  to  produce  tab- 
ular ore-bodies  known  as  "  shoots  " ;  in  the  Kalgoorlie  type  the 
struggle  between  schistosity  and  sheeting,  along  a  sheer  zone, 
produces  "  lenses.'' 


BY  THE  SECRETARY. — Comments  or  criticisms  upon  all 
papers,  whether  private  corrections  of  typographical  or  other 
errors  or  communications  for  publication  as  "Discussions,"  or 
independent  papers  on  the  same  or  a  related  subject,  are  earn- 
estlv  invited. 


SUBJECT   TO   REVISION. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Indicator  Vein,  Ballarat,  Australia. 

BY  T.    A.    RICKARD,    STATE   GEOLOGIST,    DENVER,    COLORADO. 

(Canadian  Meeting,  August,  1900.) 

IN  "  The  Genesis  of  Certain  Auriferous  Lodes  "*  Dr.  Don 
makes  a  reference  to  a  curious  vein-formation  known  as  the 
"Indicator,"  which  characterizes  a  portion  of  the  Ballarat 
mining  district,  in  Victoria,  Australia.  During  1890  and 
again  in  1898  I  had  an  opportunity  of  making  a  few  notes, 
which,  although  somewhat  belated, f  may  be  worth  adding  to 
the  observations  recorded  in  the  Transactions  of  the  Institute. 

The  country  of  the  Ballarat  gold-field  consists  of  the  Lower 
Silurian  slates  and  sandstones,  which  also  enclose  the  reefs  of 
Bendigo;  but  it  is  noteworthy  that  the  successive  anticlinal 
folds,  and  accompanying  saddles  of  quartz,  which  distinguish 
Bendigo  are  not  characteristic  of  Ballarat,  the  geological  struc- 
ture of  which  presents  greater  complexity.  . 

That  part  of  the  district  known  as  Ballarat  East  became 
famous  early  in  its  history  on  account  of  the  large  nuggets 
which  were  found  in  the  alluvium,  and  subsequently  it  became 
further  known  because  of  a  peculiar  persistent  black  seam, 
traversing  the  bed-rock  underlying  the  alluvial  deposits,  which 
was  found  to  be  associated  with  rich  bunches  of  gold-ore,  not 
only  in  the  gravel  that  capped  it  at  the  surface  but  also  in  the 
quartz-veins  which  crossed  it  underground.  The  name  of 
"  Indicator  "  was  early  given.  In  1871  Mr.  Morgan  Llewellyn 
directed  attention  to  it  as  influencing  the  distribution  of  the 
gold.  In  the  government  quarterly  report  for  December,  1888, 

*  Trans.,  xxvii.,  564  et  seq. 

t  The  treatise  contributed  by  Dr.  Don  reached  me  while  making  a  second  visit 
to  the  very  localities  among  which  he  has  gathered  so  much  valuable  evidence. 
Most  of  the  lodes  to  which  he  refers  came  under  my  own  observation  in  1889-91, 
and  though  I  have  omitted  until  now  to  join  other  members  in  acknowledging  the 
great  usefulness  of  Dr.  Don's  contribution  to  the  science  of  ore-deposits,  it  is 
solely  due  to  the  fact  that  I  had  hoped  long  ago  to  do  so  in  a  manner  which  he 
would  most  appreciate,  that  is,  by  contributing  further  data  to  the  investigations 
in  which  he  has  been  engaged. 


2  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

Mr.  E.  J.  Dunn  described*  a  similar  occurrence  observed  by 
him  in  the  neighboring  district  of  Wedderburn.  In  Septem- 
ber, 1893,  the  writer  contributed  a  note  on  the  subject,  f  Mr. 
Ernest  Lidgey,  of  the  Geological  Survey  of  Victoria,  made  a 
special  report^  on  the  Ballarat  East  gold-field,  which  was  pub- 
lished in  1894.  In  1895  and  again  in  1897  Mr.  "William  Brad- 
ford added  further  data.§ 

Mr.  Bradford,  who  lives  at  Ballarat  and  has  made  a  careful 
study  of  the  district,  describes  the  Indicator  as  "  a  pyritic 
sheet,  varying  in  width  from  one-eighth  of  an  inch  to  about  an 
inch,  which  has  been  formed  in  an  almost  parallel  line  with  the 


\\£.\  SANDSTONE  \>////\  SLATE 

The  Indicator.     (After  William  Bradford.) 

line  of  the  strata.  See  sketch."  The  sketch  referred  to  is  re- 
produced in  Fig.  1.  Another  good  illustration  from  his  later 
paper  on  the  subject  is  reproduced,  with  slight  modifications, 
in  Fig.  2.  The  indicator  is  the  dark  thread  G  B,  C  H,  which 
is  dislocated  from  B  to  C  by  the  fault-line  AD.  F  B,  C  E  is 
a  flat  seam  of  quartz  which  is  also  faulted,  with  enrichments  at 
B  and  C,  the  points  nearest  to  the  Indicator  and  to  the  later 
line  of  fracture,  A  D.  In  his  description  of  this  occurrence 
he  says : 

*  "Report  on  the  Country  in  the  Neighborhood  of  Wedderburn  and  Rheola," 
by  E.  J.  Dunn.  Quarterly  Rep.  of  the  Mm.  Dept.  of  Victoria,  1888. 

f  "Certain  Dissimilar  Occurrences  of  Gold-Bearing  Quartz."  Proc.  Col.  Sti. 
Soc.,  vol.  iv.,  pp.  329-331. 

J  "Report  on  the  Ballarat  East  Gold-field,"  by  Ernest  Lidgey,  assistant  geo- 
logical surveyor. 

$  "The  Indicator  Feature  in  Some  Gold-Occurrences,"  by  William  Bradford. 
Trans.  Austral.  Inst.  of  Min.  Enyrs.,  vol.  iv. 


THE    INDICATOR    VEIN,  BALLABAT,  AUSTRALIA. 


3 


"  Flat  make  of  quartz  displaced  by  a  slide  break.  Nuggety  gold  was  met  with 
at  the  point  where  the  Indicator  intersected  the  quartz  on  the  higher  side  of  the 
break.  Down  the  line  of  the  break  a  layer  of  gold  in  the  form  of  fine  particles 
was  found,  and  traced  to  the  point  where  the  lower  part  of  the  quartz  occurrence 
abutted  on  the  break." 

Mr.  Dunn,  the  distinguished  geologist,  whose  work  on  the 
neighboring  gold-field  of  Bendigo  is  well  known  to  the  mem- 
bers of  this  Institute,  describes  the  Indicator  at  Wedderburn 
as  being  a  "  bed  of  rock  of  dark-grey  to  black  color,  and  from 


Fig.  2 


SCALE,  'S  FEETj 

The  Indicator  Faulted.     (After  William  Bradford. ) 

5  to  7  inches  wide,  made  up  of  thinly  laminated  unctuous  clay." 
His  illustrations  are  reproduced  in  Fig.  3. 
Mr.  Lidgey,  in  his  special  report,  says : 

"These  indicators  are  usually  thin  beds  of  dark-colored  shales  and  slates, 
formed  of  a  carbonaceous  mud,  containing  a  large  percentage  of  iron  sulphide. 
They  are  parallel,  and,  so  far  as  worked,  nearly  vertical,  any  change  from  the 
vertical  being  usually  due  to  the  presence  of  faults." 

The  most  persistent  of  the  series,  known  as  "  The  Indicator," 


4  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

he  describes  as  "  a  narrow  bed  of  dark  slate,  usually  showing 
cleavage  planes,  and  containing  a  large  percentage  of  pyrite, 
distributed  irregularly  through  it."  In  Fig.  4  a  series  of  Mr. 
Lidgey's  illustrations  is  reproduced. 

Finally,  in  Fig,  5,  I  have  added  the  drawing*  exhibited  by 
me  in  1893  to  the  Colorado  Scientific  Society,  from  a  sketch 
made  at  the  700-ft.  level  of  the  New  Normanby  mine  on  Feb- 
ruary 25,  1891. 


HORIZONTAL 


Plans  of  the  Indicator  at  Wedderburn.     (After  E.  J.  Dunn,  F.  G.  S.) 

"Whatever  differences  may  be  remarked  in  the  foregoing 
descriptions  are  explained  by  the  changes  which  this  remark- 
able vein  undergoes  in  its  passage  for  seven  or  eight  miles 
through  a  long  series  of  mines,  extending  from  Black  Hill  to 
Bunninyong. 

Mr.  Lidgey's  report  is  accompanied  by  maps  of  the  Ballarat 
East  district,  exhibiting  the  course  of  the  Indicator  through  a 
series  of  claims  belonging  to  various  companies.  A  part  of 

*  This  drawing  was  reproduced  by  Dr.  Don,  on  p.  7  of  his  treatise,  and  in  his 
paper,  Trans.,  xxvii.,  570. 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 


these  maps  is  reproduced  in  Figs.  6,  7  and  8*,  which  represent 
the  plan,  cross-section  and  longitudinal  section  of  the  ground 
near  the  Prince  Regent  mine.  Further  evidence  is  given  in 
Figs.  9  and  10.  Fig.  9  is  a  photographf  taken  at  the  500-ft. 
level  of  the  No.  1  Llanberris  mine.  Fig.  10  is  a  diagrammatic 
interpretation  which  will,  it  is  believed,  aid  the  decipherment 
of  the  details  in  Fig.  9.  The  photograph  shows  the  Indicator 
(at  A  B),  and  the  foot-rule J  affords  a  scale  of  measurement ; 
yet,  as  in  most  underground  photographs,  the  dark  seams  are 
confused  by  lines  of  shadow,  and  it  is  not  possible  to  distin- 
guish the  slates  from  the  sandstones,  both  being  dark-grey  and 


Fig.  4 


567 
Diagrams  Accompanying  Report  on  Ballarat  East.     (After  E.  Lidgey. ) 

both  showing  cleavages.  Nevertheless,  it  is  a  valuable  piece 
of  evidence,  comparatively  untainted  with  the  subjective  ele- 
ment which  vitiates  a  sketch. 

By  way  of  supplementary  testimony  I  add  Figs.  11  and  12 
from  sketches  made  during  my  last  visit  to  Ballarat,  in  Janu- 
ary, 1898.  In  Fig.  11  the  Indicator  is  shown  as  seen  at  the 

*  These  three  drawings  must  not,  I  think,  be  taken  too  literally  ;  for  I  note  that 
the  stratification  of  the  slates  and  sandstones  is  repeatedly  shown  as  unbroken 
where  traversed  by  cross-courses  which,  as  is  well  known,  fault  the  country. 
Such  errors  are  doubtless  due  to  the  departmental  draughtsman  who  prepared  the 
drawings,  and  do  not  represent  any  error  of  observation  on  the  part  of  Mr.  Lidgey 
himself.  It  was  the  dislocation  of  the  Indicator  series  that  the  drawings  were 
intended  to  represent  ;  and  this  they  do  satisfactorily. 

t  Thi    excellent  photograph  was  kindly  given  to  me  by  Mr.  Lidgey  in  1898. 

+  Which,  it  should  be  noticed,  is  extended  so  as  to  cover  a  length  of  2  feet. 


6  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

770-ft.  level  of  the  Prince  Regent  mine,  where  it  is  dislocated 
by  a  flat  seam  of  quartz  which  carries  coarse  gold  at  the  cross- 


Fig.  5 


The  Indicator,"  New  Normanby  Mine,  Ballarat,  Australia. 


ing.     The  Indicator  evidently  conforms  to  the  bedding  of  the 
slate  band,  of  which,  indeed,  it  forms  a  part. 

The  Metropolitan  lode,  illustrated  in  Fig.   12,  occurs  in  an 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA.  7 

adjacent  portion  of  the  Ballarat  district.  It  has,  on  a  large 
scale,*  certain  of  the  features  which  characterize  the  geological 
structure  of  the  Indicator  series,  and  for  this  reason  it  is  placed 
in  evidence  here.  The  Metropolitan  lode  consists  of  a  series 
of  spreading  quartz-seams,  to  be  considered  as  branches  thrown 
out  by  nearly  vertical  veins,  traversing  a  band  (A  B,  C  D)  of 
thinly-bedded  slates  and  sandstones,  and  dips  slightly  westward 
from  the  vertical.  This  band,  which  is  enclosed  by  a  series  of 
massive  beds  of  sandstone,  forms  a  lode,  or  lode-channel,  80 
ft.  wide,  in  which  the  quartz-seams  first  referred  to  rarely  ex- 
ceed 7  or  8  ft.  in  thickness,  and,  having  an  easterly  dip,  cross 
the  bedding  almost  at  right  angles.  The  cross-veins  recognize 
the  structure  of  the  rocks  they  traverse  by  a  succession  of  drops 
as  they  meet  the  successive  seams  of  slate.  The  gold-occur- 
rence is  also  modified  by  this  structure,  the  richest  quartz  being 
found  at  the  crossing  of  the  slates,  and  especially  upon  the 
lower  or  eastern  side.  The  quartz  composing  these  seams  is 
white  "  as  a  hound's  tooth;"  but  occasionally,  in  the  slate,  it  is 
besprinkled  with  a  little  arsenical  pyrite. 

The  Indicator  is  essentially  a  very  thin  thread  of  black  slate, 
which  is  remarkable  on  account  of  its  extraordinary  persistence, 
and  also  because  the  quartz  seams  which  cross  it  are  notably 
enriched  at  the  place  of  intersection.  In  certain  parts  of  Bal- 
larat East  the  Indicator  has  coincided  with  lines  of  movement, 
and  having,  on  this  account,  undergone  attrition,  it  now  ap- 
pears as  a  seam  of  clay.  At  other  places  it  is  so  impregnated 
with  iron  pyrites  as  to  have  the  characteristics  of  a  sulphide 
streak.  When  it  is  met  by  quartz-veins  carrying  galena  and 
zinc-blende  it  partakes  of  their  mineralization.  At  the  end  of 
the  700-ft.  level  in  the  New  Normanby  mine  it  was  slightly 
over  one-sixteenth  of  an  inch  thick,  and  consisted  of  crushed 
black  slate,  in  which  small  crystals  of  pyrites  were  embedded. 
In  a  cross-cut  nearby  it  appeared  as  a  thin  vein  of  quartz.  This 
is  an  infrequent  modification,  and  one  which  is  found  by  expe- 
rience to  be  unfavorable  to  the  occurrence  of  rich  ore.  At  the 
770-ft.  level  of  the  Prince  Eegent  mine  the  Indicator  had  the 
thickness  of  an  English  penny,  and  was  freely  studded  with 
crystals  of  arsenical  pyrites,  tarnished  by  oxidation. 

The  belt  of  slates  and  sandstones  constituting  the  prevailing 

*  The  scale  of  Fig.  12  represents  feet,  and  not  inches,  as  in  Fig.  11. 


8  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

geological  formation  of  the  district  is  marked  by  a  peculiarly 
persistent  series  of  thin  seams  of  black  slate.  The  Indicator 
is  the  chief  member  of  this  series,  by  reason  both  of  its  per- 
sistence and  of  its  economic  importance  as  marking  a  line  of 
particular  enrichment.  The  others  are  variously  known  as  the 
"  Western  Indicator,"  the  "  Pencil  Mark,"  the  "  Nuggety 
Slate,"  "Dunk's  Slate,"  "The  Streaky  Slate,"  etc.,— an  odd 
nomenclature,  originating  with  the  miners,  who  have  been 
quick  to  recognize  these  various  "  leaders,"  as  they  have  been 
encountered  in  the  workings  underground.  This  series  is 
crossed  by  a  later  system  of  quartz-veins  and  stringers,  inter- 
secting the  bedding  of  the  sedimentary  rocks  almost  at  right 
angles,  and  lying,  therefore,  approximately  flat,  with  a  slight 
dip  northeast.  Occasionally,  large  quartz-veins  are  seen  follow- 
ing the  planes  of  bedding;  but  such  as  do  so,  appear  invariably 
to  be  poor.  Those  which  cross  the  Indicator  (and  its  com- 
panion-seams) are  gold-bearing,  but  only  at  the  places  where 
they  intersect  the  Indicator,  and,  as  will  have  been  noted  in  the 
illustrations,  fault  it.  Therefore  the  workings  follow  the  Indi- 
cator in  such  a  way  that  the  rock  removed  includes  2  or  3  ft.* 
on  either  side  of  it.  The  intersecting  quartz-seams  are  so  fre- 
quent that  the  entire  band  along  the  line  of  the  Indicator  is 
treated  as  a  gold-bearing  lode.  Poor  zones  occur.  Thus  the 
Prince  Regent  mine  has  found  no  pay-ore  on  the  Indicator  be- 
tween the  550-ft.  level  and  the  770-ft.  level.  The  Speedwell 
mine  traversed  a  barren  interval  between  400  and  500  ft.,  but 
is  said  to  have  become  profitable  lower  down.  There  is,  how- 
ever, at  the  present  time,  a  general  tendency  toward  impover- 
ishment in  the  deeper  workings  of  the  group  of  mines  occu- 
pying the  Indicator  belt. 

The  series  of  quartz-seamsf  which  intersect  the  Indicator 
are  not  to  be  considered  as  isolated  lenticles,  but  must  be  re- 
garded as  part  of  an  extensive  system  of  flat  veins,  which  are 
lateral  embranchments  from  the  nearly  vertical  ones  to  be  seen 
following  the  bedding  of  the  slates  and  sandstones,  as,  for  ex- 
ample, along  B  D,  in  Fig.  12.  The  workings  of  the  mines  ex- 
hibit frequent  lines  of  faulting,  or  "  slides,"  which  dislocate  the 
entire  series  referred  to,  i.e.,  the  Indicator,  the  quartz-seams  en- 

*  As  a  rule  a  few  inches  on  either  side  of  the  Indicator  represents  the  entire 
width  of  the  pay- ore,  but  4  to  5  ft.  is  necessarily  removed  for  convenience  of  ex- 
ploitation, f  The  Australian  miner  calls  these  "makes  of  spurs." 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA.  9 

riched  by  it,  and  the  enclosing  slates  and  sandstones.  These 
"  slides "  carry  clay  and  exhibit  the  other  characteristics  of 
planes  along  which  a  movement  of  the  rocks  has  taken  place. 


Mr.  William  Chisholm,  the  manager  of  the  Prince  Regent 
mine,  who  is  thoroughly  familiar  with  the  geological  structure 
of  this  part  of  Ballarat,  regards  the  impoverishment  below  the 


10 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 


_  _CR08SfpUR8E      NO.  29 
/   1  T 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 


11 


550-ft.  level  as  connected  with  the  "  big  slide "  which  cuts 
through  the  shaft  540  ft.  below  the  surface  and  shifts  the  Indi- 
cator series  55  ft.  westward.  The  managers  of  the  neighbor- 
ing properties  also  connect  similar  disturbances  encountered  in 
the  workings  of  their  mines  with  the  diminution  in  the  rich- 
ness of  the  series  of  flat  quartz-veins.  Dr.  Don  takes  this  view, 
and  confirms  it  with  analyses  of  samples  taken  in  the  Prince 
Regent  mine,  which  prove  that  the  solid  country  enclosing  the 
veins  is  not  itself  gold-bearing,  while  the  clay  accompanying 


yy__SURFAC_E 


Fig.  8 

DALZELL  PRINCE  REGENT 


Cross-Section  of  Fig.  6.     (After  E.  Lidgey,  Geological  Survey  of  Victoria, ) 

the  fault-fracture  is  rich  in  gold.  In  both  cases,  the  presence 
of  gold  bore  no  relation  to  the  richness  or  poverty  of  the  neigh- 
boring Indicator. 

These  views  seem  to  me  to  be  in  accord  with  the  evidence ; 
but  until  the  present  horizon  of  impoverishment  which  charac- 
terizes the  lower  workings  of  the  mines  of  Ballarat  East  is 
succeeded,  deeper  down,  by  a  horizon  of  enrichment,  one  is 
scarcely  warranted  in  speaking  of  "  zones."  My  experience  is, 
I  believe,  in  accord  with  that  of  most  of  us,  in  recognizing  the 


12  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

fact  that  gold-veins  often  get  poorer  in  depth ;  and  this  occur- 
rence is  so  frequent  that  a  particular  explanation,  like  the  one 


FIG. 


The  Indicator,  500-ft.  Level  No.  1,  Llanberris  Mine. 

above  mentioned,  gains  no  force  by  being  connected  with  such 
a  general  fact.     A  zone  of  impoverishment  is  usually  only  a 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 
Fig.  10 


13 


kWfrA*J?$  feli?l5* 


'    '     \[    I  SLATE  AND  SANDSTONE.  I  INDICATOR, 

The  Indicator.     Diagram,  Explaining  Fig.  9. 

euphuism  calculated  to  obscure  the  frank  recognition*  of  things 
as  they  are. 

*  I  was  glad  to  read  Dr.  Don's  frank  statement  (op.  cit.,  p.  596)  concerning  this 
matter  of  impoverishment  below  the  water-level.     Science  has  to  do  with  facts  ; 


14 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 


The  enrichment  of  the  selvage  accompanying  the  fault- 
planes,  as  proved  by  Dr.  Don,  is  very  suggestive.  If  these 
faults  served  as  passages  for  the  upward  circulation  of  the  gold- 
bearing  solutions  which  precipitated  a  part  of  their  precious 
burden,  en  route,  and  the  remainder  when  the  Indicator  seams 
were  intersected,  then  we  have  a  very  pretty  example  of  ore- 
Fig.  1 1 


M 
"ill 

0      1     2     :i     4      5      0 
SCALE  OF  INCHES 


Kl-"™ 


I' 


The  Indicator,  Prince  Regent  Mine,  Ballarat. 

deposition.  As  yet,  however,  the  evidence  does  not  go  much 
further  than  to  accentuate  the  coincidence  between  the  occur- 
rence of  rich  gold-ore  and  a  casing  of  carbonaceous  rock.  The 
organic  matter  observed  in  the  Indicator  seam,  and  also  in  the 
clay  following  the  faults,  is  of  particular  interest,  because  it 
agrees  with  similar  observations  made  in  other  mining  regions. 

nor  can  the  industry  of  mining  which  is  based  upon  the  application  of  science  be 
aided  by  fancies,  however  alluring. 


THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 


15 


The  graphitic  slates  of  the  neighboring  district  of  Bendigo  ap- 
pear to  have  exerted  a  favorable  influence  on  the  deposition  of 
gold.  These,  like  those  of  Ballarat,  are  of  Lower  Silurian  age, 
but  the  same  coincidence  marks  the  Devonian  shales  of  Gympie, 
in  Queensland,  and  the  Jurassic  slates  of  California.  Small 
patches  of  peculiarly  beautiful  crystalline  gold  are  found  in  the 
black  Cretaceous  shales  of  Farncomb  hill,  at  Breckenridge, 


SCALE  OF  FEET 


The  Metropolitan  Lode. 

Colorado ;  and  at  Rico,  in  the  same  State,  a  series  of  black 
shales  and  limestones  of  Lower  Carboniferous  age  enclose  the 
richest  portion  of  a  very  extensive  series  of  veins.  In  these 
cases  the  blackness  represents  the  carbonaceous  remnant  of 
vegetable  matter  which  was  mingled  with  the  silt  and  slime  out 
of  which  the  slates  and  shales  were  formed.  In  the  case  of  so 
persistent  and  thin  a  seam  as  the  Indicator  we  have  to  suppose 


16  THE    INDICATOR    VEIN,  BALLARAT,  AUSTRALIA. 

an  extremely  slow  sedimentation,  occurring  in  a  large  sheet  of 
water  undisturbed  by  cross-currents.  The  clay  of  the  "  slides," 
examined  by  Dr.  Don,  must  have  derived  its  carbonaceous  con- 
stituent through  mechanical  action  upon  the  edges  of  the  slate- 
beds  crossed  by  the  line  of  faulting;  the  softer  members  of  the 
series  being,  as  I  remember,  the  blackest. 

This  association  of  gold  and  carbonaceous  matter  has  been 
investigated  by  Dr.  Don  with  negative  results,  not  only  at 
Ballarat  but  also  at  Gympie.  It  would  appear  that  where  the 
black  slates  are  gold-bearing  they  also  carry  a  notable  amount 
of  pyrites.  This  was  so  at  Rico,  where  I  was  able  to  make  a 
careful  study*  of  the  veins  which  seemed  to  have  been  favor- 
ably affected  by  a  graphitic  encasement.  But  Dr.  Don  was 
looking  in  the  enclosing  rocks  for  the  source  of  the  gold,  and 
not  for  a  precipitant,  because  he  is  impressed  with  the  fact  that 
gold  is  so  easily  precipitated  from  its  solutions  that  it  is  scarcely 
necessary  to  seek  for  a  special  agent.  Nevertheless}  accepting 
as  I  do  the  general  theory  of  an  ascending  circulation  as  the 
basis  of  a  science  of  ore-deposits,  it  seems  to  me  that  it  is  for 
the  causes  favoring  precipitation  that  we  must  seek  if  we  are 
to  understand  the  vagaries  of  gold-occurrence.  The  experi- 
ments f  made  with  the  Rico  shale  illustrated  the  rapidity  with 
which  gold  is  precipitated  from  certain  solutions  when  they 
come  in  contact  with  such  carbonaceous  matter.  That  there  is 
also  much  black  slate  and  graphitic  shale  which  is  not  remark- 
able for  containing  rich  gold-veins,  is  no  particular  argument 
against  the  value  of  the  observation.  The  carbonaceous  mat- 
ter was  probably  only  one  out  of  several  factors  which  favored 
the  precipitation  of  the.  gold ;  and  the  pyrite,  having  been  de- 
posited previous  to  the  gold,  was  probably  another.  But  how- 
ever that  may  be,  it  is  an  inquiry  which  must  be  left  to  pains- 
taking investigators  like  Dr.  Don,  and  not  to  mining  engineers, 
who,  like  the  writer,  have  not  the  time  or  the  ability  for  such 
work.  For  us,  and  for  the  miners  whom  we  direct,  it  is  well 
to  emphasize  the  fact  that  certain  observed  conditions,  struc- 
tural or  physical,  are  favorable  to  the  finding  of  gold ;  and  if, 
in  our  daily  work,  we  can  collect  further  observations  of  this 
kind  we  shall  have  done  something  to  aid  the  endeavors  of  the 
specialists  who  are  patiently  trying  to  unravel  the  mysteries 
which  beset  the  genesis  of  ore-deposits. 

*  "The  Enterprise  Mine,  Eico,  Colorado,"  Trans.,  xxvi.,  906. 


[TRANSACTIONS  OF  THE  AMERIC\N  INSTITUTE  OF  MINING  ENGIN1  ERS.] 


The  Alluvial  Deposits  of  Western  Australia. 

BY  T.    A.    RICKARD,    STATE   GEOLOGIST,    DENVER,   COLORADO. 

(Buffalo  Meeting,  October,  1898.) 

I. — GENERAL  GEOLOGICAL  CONSIDERATIONS. 

THE  interior  of  West  Australia  is  an  arid  table-land,  elevated 
1400  feet  above  the  sea.  This  plateau  is  flanked  to  the  south 
by  the  Tertiary  limestones  which  fringe  the  Great  Australian 
Bight.  It  is  bordered  northward  by  the  Carboniferous  beds  of 
the  Fitzroy  river  and  westward  by  the  granite  of  the  Darling 
hills,  while  to  the  east  this  wide  area,  about  900  miles  square, 
slopes  downward  imperceptibly  into  an  undulating  plain  of 
sand,  which  stretches  with  dismal  persistence  across  the  boun- 
dary of  South  Australia.  The  waters  of  the  ocean  receded 
from  this  tract  of  land  long  ago ;  it  is  probably  the  oldest  land- 
surface  on  the  globe,  and  represents  the  basal  wreck  of  a  much 
larger  continent.  Fig.  1  is  a  map  of  this  region. 

The  Coolgardie  and  Kalgoorlie  gold-fields  are  situated  in  the 
southwestern  part  of  the  region.  The  rock-formation  consists 
of  granite  penetrated  by  diorites  and  andesites.  The  latter  are 
occasionally  associated  with  tuffs,  which  have  been  readily  mis- 
taken for  sedimentaries.  There  are  no  fossil-bearing  rocks, 
such  as  would  afford  a  datum-line  from  which  to  measure  the 
relative  geological  age  of  the  prevailing  formation.  On  the 
extreme  edges  of  the  mining  territory  there  are,  it  is  true, 
remnants  of  sand-rock  which  are  considered  identical  with 
the  "  Desert  Sandstone  "  of  Queensland,  determined  by  Dain- 
tree  to  be  of  Mesozoic  age.  But  even  this  formation  has 
evidently  been  laid  down  so  long  subsequent  to  the  underlying 
rocks  that  it  serves  merely  to  emphasize  their  much  greater 
antiquity. 

In  their  characteristics  and  in  their  relations  to  each  other, 
the  granite  and  the  diorite  of  the  Coolgardie  region  appear  to 
me  much  to  resemble  the  Laurentian  granite  and  the  Huronian 


2  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

schists  of  Ontario,  in  Canada.*  Their  age  can  only  be  vaguely 
described  as  Archaean. 

On  many  parts  of  the  earth's  surface  a  long-continued,  slow 
movement  of  continental  uplift,  interrupted  by  intermittent 
periods  of  rest  or  subsidence,  has  permitted  the  transfer  of  land 
to  the  sea  by  the  erosion  of  the  exposed  parts  and  the  depo- 
sition of  their  detritus  as  ocean  sediment,  thus  causing  the  up- 
building of  a  mountain-system  composed  of  a  series  of  rocks 
belonging  to  successive  epochs.  In  this  particular  region,  on 
the  contrary,  all  diversity  is  wanting,  and  a  sameness  of  aspect 
wearies  the  observer.  In  the  absence  of  an  elevatory  move- 
ment, more  than  sufficient  to  balance  the  slow  degradation  of 
the  higher  parts  of  the  region,  there  has  been  no  compensation 
for  the  effects  of  atmospheric  erosion,  so  that  this  tract  has  be- 
come a  dreary  flat,  strewn  with  the  sandy  wreck  of  weathered 
rocks. 

The  United  States  offers  both  a  contrast  and  a  parallel.  In 
the  Rocky  Mountain  region  the  movement  of  uplift  which  com- 
menced in  pre-Cambrian  times  has  only  been  interrupted  so  as 
to  permit  of  the  laying-down  of  younger  sediments ;  and  the 
degradation  of  the  high  places  has  been  compensated,  and 
sometimes  exceeded,  by  an  elevation  which  has  resulted  in  the 
formation  of  a  mountain  mass  flanked  by  a  long  succession  of 
strata  now  enclosing  a  great  variety  of  mineral  wealth.  The 
interior  of  Australia  can  be  likened  to  the  Great  Basin,  occu- 
pied by  Nevada  and  parts  of  Utah,  Idaho  and  Arizona,  between 
the  Rocky  Mountains  themselves  and  the  Sierra  Nevada.  There 
is  only  one  large  river  in  Australia  which  reaches  the  sea, 
namely,  the  Murray,  which  rises  near  the  boundary-line  of  Vic- 
toria and  New  South  Wales,  and  then  flows  toward  the  inte- 
rior, to  be  saved  by  a  backward  sweeping  curve,  which  permits 
the  river  at  length  to  empty  itself  into  the  sea  at  the  border  of 
South  Australia.  There  are  many  "  lost  rivers,"  like  the  Carson 

*  The  mass  of  the  granite  is  penetrated  by  the  mass  of  the  diorite,  the  latter 
being  therefore  the  younger ;  but  puzzling  evidence  is,  afforded  by  the  fact  that 
the  diorite  at  the  contact  is  sometimes  traversed  by  embranchments  of  gran  te, 
which  are  explainable  on  the  supposition  that  subsequent  metamorphism  gave  the 
granite  a  renewed  mobility,  permitting  it  to  penetrate  fractures  in  the  diorite. 
At  Rat  Portage,  Ontario,  the  overlying,  younger  Huronian  schists  are  inter- 
calated and  penetiated  by  the  older  Laurentian  granite  at  certain  places  along  the 
line  of  contact. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA. 
FIG.  1. 


WESTERN  AUSTRALIA 


PROCLAIMED   GOLDFIELDS 


REFERENCE: 

Railways  open  for  Trade     

Railways  under  Construction 

Boundaries  of  Gold  Fields 
Stock  Routes 


KMtefi      oH7     . 

Soutli 


V    \™a\tF3»* 


AMERICAN    BANK   NOTE   CO.  NEW    YORK 


4  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

and  the  Humboldt  in  Nevada.  During  the  rainy  season  they 
are  tempestuous  torrents ;  during  the  succeeding  dry  months 
their  course  is  marked  by  sandy  bottoms,  dotted  with  an  occa- 
sional water-hole.  The  mountains  are  near  the  coast,  so  that 
the  Australian  Alps  and  the  Blue  Mountains  do  the  same  ser- 
vice as  the  Sierra  Nevada  and  the  Cascades,  in  that  they  inter- 
rupt the  warm,  moisture-laden  winds,  and  compel  them  to  pre- 
cipitate on  the  seaward  slope.  The  consequence  is  that  the 
eastern  parts  of  the  colonies  of  Queensland,  New  South  Wales 
and  Victoria,  between  the  mountains  and  the  sea,  resemble  the 
valleys  of  California  and  Oregon,  just  as  the  interior  region 
beyond  them  bears  a  likeness  to  the  dry  tracts  of  Nevada  and 
Arizona. 

The  sea  retired  from  the  interior  of  West  Australia  in  the 
very  dawn  of  geological  time,  and  the  movement  of  elevation, 
which  raised  the  land  above  the  waters,  continued  with  but 
little  interruption  until  the  beginning  of  the  Tertiary  period. 
Since  then,  slow  subsidence  has  robbed  the  Australian  conti- 
nent of  a  part  of  its  extent,  and  made  Tasmania  an  island. 
There  is  evidence  of  a  much  larger  continental  area,  which  at 
one  time  extended  toward  Southern  Africa.  The  encroachment 
of  the  sea  has  crowded  a  wonderful  variety  of  flora  into  the 
small  stretch  of  fertile  country  lying  between  the  desert  and 
the  Indian  Ocean.* 

The  main  drainage  of  the  interior  is  to  the  south.  The  last 
retreat  of  the  sea  was  accompanied  by  the  formation  of  broad 
valleys,  which  have  lost  their  former  outlines,  and  now  ap- 
pear as  long  depressions,  largely  filled  up  with  the  products 
of  erosion. 

II. — THE  PHYSIOGRAPHY  OF  THE  GOLD-FIELDS. 

The  principal  gold-field  of  West  Australia  is  situated  in  the 
southwestern  part  of  the  desert  plateau.  The  chief  towns  are 


*  This  corner  of  Australia  is  celebrated  among  botanists  for  the  extraordinary 
variety  of  its  flora.  Baron  Ferdinand  von  Mueller,  the  celebrated  botanist,  may 
be  quoted :  "  A  marvellous  exuberance  of  plants,  different  in  species,  and  often 
gay  or  odd  in  aspect,  exists  within  a  triangle  formed  by  a  line  of  demarkation 
drawn  from  the  south  of  Sharks  Bay  to  the  west  of  the  Great  Bight ;  and  within 
this  space  are  chiefly  located  those  species  which  are  exclusively  restricted  to  West 
Australian  territorv." 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  5 

Coolgardie  and  Kalgoorlie.*  They  are  connected  by  350  miles 
of  railway  with  the  coast  During  the  year  1897  the  total  rain- 
fall amounted  to  5f  inches  at  the  one  place  and  4|  inches  at 
the  other,  f  In  contrast  to  these  figures,  it  may  be  added  that 
the  rate  of  evaporation  in  this  region  is  estimated  to  be  equiva- 
lent to  7  feet  per  annum. 

The  country  consists  of  a  sandy  plain,  the  monotony  of  which 
is  intensified  by  a  series  of  alternating  low  rocky  ridges  and 
equally  slight  depressions,  having  a  northwesterly  direction. 
Most  maps  indicate  the  occurrence  of  lakes  and  the  occasional 
course  of  a  stream,  but  these  are  the  mirages  of  the  cartog- 
rapher. The  "  lakes  "  are  shallow  basins  with  clay  bottoms,  in 
which,  during  the  rainy  season,  a  little  water  lingers,  and  the 
"  streams  "  are  sandy  channels,  where  sinking  will  sometimes 
tap  a  trickling  flow  of  brine. 

The  surface  is  devoid  of  vegetation,  except  in  spring,  when 
flowersj  of  a  brilliant  hue,  but  with  the  texture  of  hay,  leap 
into  brief  existence.  Animal  life  is  infrequent.  An  occasional 
bustard  may  be  provoked  into  leisurely  flight,  a  troop  of  paro- 
quets throws  a  momentary  gleam  athwart  the  dull  gray  of  the 
bush,  or  a  solitary  kangaroo  hops  across  the  trail.  These,  how- 
ever, are  but  infrequent  interruptions  to  the  sullen  silence  of 
the  wilderness. 

The  real  nakedness  of  the  region  is  hidden  by  the  "  bush," 
consisting  of  scrub  from  20  to  60  feet  high,  chiefly  mulga  and 
ti-tree.§  This  covers  all  things  as  with  a  garment  (see  Fig.  2). 
The  roads  are  cut  through  it  with  the  monotonous  regularity 
of  a  canal.  One  portion  ot  the  journey  is  but  the  counterpart 
of  another.  The  sameness  is  wearisome  beyond  words.  And 

*  These  localities  are  not  found  save  on  recent  maps.  Kalgoorl'e  is  in  latitude 
3  J°  4V  south  and  longitude  121°  30'  east,  while  Coolgardie  lies  in  latitude  30°  57' 
south  and  longitude  121°  10'  east.  They  are  25  miles  apart. 

t  The  rainfall  at  Denver  is  14£  ;  Alexandria,  10 ;  Paris,  22 ;  London,  35  ; 
Canton,  39  ;  Calcutta,  76;  Vera  Cruz,  180;  and  at  Cherrapongee,  in  Assam,  610 
inches  per  annum. 

J  The  "  Everlastings,"  as  they  are  usually  called,  belong  chiefly  to  the  genera 
Helichrysum,  Helipterum,  "NVaitzia,  Podolepis  and  Angianthus.  For  about  three 
months  they  appear  as  magnificent  splashes  of  color,  carpeting  the  desert  with 
splendor.  They  are  wholly  devoid  of  perfume,  and  have  the  brittle  texture  of 
artificial  flowers. 

\  Both  acacias.  The  characteristic  tree-shrubs  of  the  country  belong  to  the 
genus  Acacia.  Many  of  them  have  a  fragrant  bloom  in  the  spring. 


6  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

when  an  elevated  spot  is  attained  the  eye  commands,  from 
north  to  south,  from  east  to  west,  one  dark  unbroken  sea  of 
trackless  hush. 

Gold-mining  caused  this  desert  to  be  invaded.  The  first  dis- 
covery was  made  by  Anstey,  in  1887,  at  Yilgarn,  which  is  210 
miles  east  from  Perth,  the  capital  of  the  colony.  This  started 
the  Southern  Cross  mining  district.  Prospectors  began  to 
scatter  further  inland.  In  1892  Bayley  made  the  discovery 
which  marked  the  birth  of  Coolgardie,  and  the  commencement 
of  an  activity  which  culminated  in  the  mining  excitement  of 
1895.  A  series  of  rich  finds,  scattered  over  the  surrounding 
desert,  gave  rise  to  the  settlements  of  Menzies,  Goongarrie, 
Kanowna,  Kurnalpi,  Kunanalling,  "Wagiemoola,  and  a  score  of 
other  patches  of  corrugated-iron  hideousness  labeled  with 
euphonious  aboriginal  names.  In  June,  1893,  Patrick  Hannan 
pegged  out  a  discovery-claim  at  Kalgoorlie,*  25  miles  east  of 
Coolgardie.  The  find  which  he  made  was  of  no  particular  im- 
portance, and  the  neighboring  area,  like  many  others,  became 
the  scene  of  the  purposeless  digging  which  was  at  that  time 
sufficient  to  give  an  impetus  to  a  great  deal  of  reckless  com- 
pany-promoting. However,  just  as,  in  Colorado,  the  Mt.  Pisgah 
fiasco  of  1884  preceded  the  real  development,  eight  years  later, 
of  Cripple  Creek,  so  the  vagaries  of  irresponsible  schemers  led 
to  the  accidental  opening  up  and  the  eventual  recognition  of  the 
magnificent  series  of  rich  lodes  that  have  now  placed  Kalgoorlie 
among  the  few  great  mining  camps  of  the  globe. 

In  1897  West  Australia  produced  674,993  ounces  of  gold,  to 
which  Kalgoorlie  alone  contributed  306,000  ounces.  During 
the  same  period  the  mines  of  the  colony  paid  $2,400,420  in 
dividends,  and  out  of  this  total  Kalgoorlie  is  credited  with 
$1,775,000.  The  growth  of  the  industry  is  exhibited  by  the 
accompanying  statistics : 

Kalgoorlie.  West  Australia. 
Year.                                                                      Ounces.  Ounces. 

1895,  .        .        ;        .        .        .        .       36,000  231,513 

1896,  .        .        ....         .         .     103,000  281,265 

1897,.        *        .        ....     306,000  674,993 

It  is  estimated  that  the  yield  of  the  colony  for  the  current 

*  See  the  interesting  paper  of  my  friend,  Mr.  George  J.  Bancroft,  ' '  Kalgoorlie, 
Western  Australia,  and  Its  Surroundings,"  read  at  the  Atlantic  City  Meeting, 
February,  1898. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  7 

year  will  reach  a  million  ounces,  and  that  of  this  one-half  will 
come  from  the  Kalgoorlie  district. 

The  development  of  a  group  of  very  rich  telluride  lodes  amid 
this  immense  desert  country,  dotted  over  with  the  unhappy 
failures  which  were  based  on  small  pockets  of  specimen  gold- 
quartz,  did  not  happen  without  a  sad  expenditure  of  money  and 
human  life.  "With  the  whisper  of  every  new  discovery,  crowds 
of  reckless  gold-seekers  plunged  madly  into  the  outer  desolation. 
Eager  horsemen  jostled  the  awkward  camels,  whose  swinging 
gait  carried  them  in  turn  past  the  mohs  of  diggers  who  trudged 
wearily  to  the  scene  of  each  successive  excitement.  One  knows 
not  whether  to  admire  the  pluck  or  to  deride  the  foolishness  of 
men  who  died  of  thirst  and  perished  of  fever  in  the  mad  search 
for  gold.  The  incident  known  as  "  the  Siberia  rush  "  will  be 
typical  of  early  days.  A  man  came  into  Coolgardie  one  night 
with  a  story  that  gold  had  been  found  at  a  locality  thirty-odd 
miles  to  the  north.  Hundreds  started  off  on  horses  or  on 
camels ;  many  went  on  foot,  carrying  their  billies*  and  blankets 
upon  their  shoulders  or  trundling  their  packs  in  wheelbarrows. 
Some  took  the  wrong  direction,  and  of  these  many  never 
reached  their  destination,  but  died  miserably  in  the  bush. 
Four  hundred  eventually  reached  Siberia,  f  The  only  water 
near  the  discovery  was  a  soak,|  seven  miles  distant.  It  was 
soon  drained  dry  by  the  crowd  of  diggers,  l^ews  came  to 
Coolgardie  that  a  water-famine  was  imminent.  The  superin- 
tendent of  water-works,  a  government  officer,  instantly  de- 
spatched a  dozen  camels  §  to  the  succor  of  the  adventurers.  In 
the  meantime,  they,  realizing  the  impending  danger,  had  left 
the  gold,  and  were  making  for  the  nearest  condenser.  ||  Many 
died  on  that  return  journey,  and  many  more  would  have  been 
lost  save  for  the  water  brought  by  the  camel-train.  But  in  a 
few  days  there  was  another  stampede  in  another  direction. 
Thus  the  gold-fields  were  opened  up.  Sic  Etruria  crevit. 

*  The  "billy"  is  the  tinned-iron  vessel,  of  from  2-  to  4- quart  capacity,  in 
which  the  miner  makes  his  tea  and  does  his  cooking. 

f  What  a  satire  is  the  name  !  The  locality  has  a  mean  annual  temperature  of 
78°,  and  the  summer  heat  is  112°  to  120°  in  the  shade. 

|  A  "soak"  is  the  morass  of  the  desert,  where  water  has  accumulated  in  a  de- 
pression, and  is  got  by  digging  through  the  sand  which  covers  it. 

%  A  camel  carries  two  tins,  each  holding  '10  gallons. 

||  All  the  drinking-water  is  the  product  of  the  ''condenser,"  of  which  a  de- 
scription is  given  below.  See  Figs.  3,  4,  24,  and  25. 


8  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

The  peculiar  character  of  these  "  rushes  "  is  directly  traceable 
to  the  nature  of  the  gold-occurrence.  Gold  is  found  lying  on 
the  very  top  of  the  ground,  and  the  first  surface-mining  yields 
extraordinary  profits.  The  search  for  the  particles  of  gold 
scattered  over  the  surface  is  called  u  specking."  In  the  early 
days  hundreds  of  ounces  were  thus  picked  up  in  a  few  hours 
by  the  men  first  to  reach  a  rich  spot.  When  the  cream  has 
thus  been  skimmed  off,  the  sandy  soil  underneath  is  treated, 
the  dirt  being  winnowed  by  pouring  it  from  one  pan  into 
another.  After  that,  actual  digging  begins,  the  shallow  deposits 
being  trenched  and  pitted  in  the  search  for  those  patches  of 
rich  ground  through  which  the  gold  is  found  sporadically  dis- 
tributed. "  Specking "  is  still  a  recognized  occupation  on 
Sundays,*  even  at  the  established  mining  centers.  I  have  seen 
as  many  as  a  hundred  men  walking  about  with  their  hands  in 
their  pockets  and  their  eyes  intent  on  the  ground,  for  all  the 
world  as  if  they  were  in  disgrace.  A  five-ounce  nugget  may 
be  found ;  and  everyone  hastens  to  the  spot.  Perhaps  nothing 
more  is  picked  up;  or  it  may  be  that  sufficient  gold  is  dis- 
covered to  attract  troops  of  "  dry-blowers"  to  the  place.  The 
"  dry-blower "  is  brother  to  the  "  gulch-miner "  of  America 
and  the  "  alluvial  digger  "  of  the  eastern  colonies  of  Australia. 
In  the  investigation  of  the  methods  of  the  dry-blower  and  the 
occurrence  of  the  deposits  out  of  which  he  wins  the  gold,  I 
observed  many  facts  of  such  interest,  it  seemed  to  me,  as  to 
warrant  the  preparation  of  this  contribution  to  the  Transactions 
of  our  Institute. 

In  mountainous  regions  the  disintegration  of  the  surface  is 
mainly  caused  by  the  frost.  Water  penetrates  into  crevices 
and  cracks,  and,  because  its  maximum  density  is  at  4°  C.  and 
not  at  zero,  it  undergoes  such  expansion  in  the  immediate  ap- 
proach to  the  freezing-point  as  to  become  a  powerful  lever  for 
tearing  the  rocks  apart.  Thus  is  loosened  that  material  out  of 
which  eventually  the  alluvial  deposits  of  the  valley  are  formed. 
In  warmer  climates  the  contraction  and  expansion  of  water  is 
likewise  a  ceaselessly  destructive  agent.  Even  in  a  dry,  hot, 
region,  such  as  the  interior  of  West  Australia,  the  difference 


*  Sunday  labor  is  generally  forbidden  throughout  the  Australian  colonies  ;  hence 
the  opportunity  to  go  "specking,"  as  above  described. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  9 

between  the  heat  of  day  and  the  cold  of  night  causes  the  dew 
to  play  an  important  part  in  moulding  the  physiography  of  the 
country.  For  it  must  be  remembered  that  the  changes  of 
volume  caused,  in  water  as  in  other  substances,  by  changes  of 
temperature,  are  well-nigh  irresistible  in  energy,  however  minute 
in  amount.  The  cool  nights,  which  alone  make  life  bearable 
on  the  Coolgardie  gold-fields,  are  thus  beneficent  in  two  ways. 
To  them  is  ultimately  owing  the  formation  of  those  accumula- 
tions of  gold-bearing  dirt  out  of  which  many  a  prospector  has 
dug  himself  a  competence  for  life.  The  tables  on  page  10  from 
the  government  meteorological  reports  exhibit  this  variation 
in  temperature. 

In  mountainous  lands  the  melting  of  the  winter  snows  yields 
the  water  employed  in  that  process  of  concentration  which 
begins  as  soon  as  the  rock  is  shattered,  and  continues  until 
each  ultimate  particle  has  been  classified  by  the  untiring  ma- 
chinery of  nature.  The  "  tailings  "  are  the  mud  and  sand  \vhich 
go  to  build  new  continents  upon  the  ocean-floor,  the  "  mid- 
dlings "  are  the  great  masses  of  alluvium  covering  the  plain, 
and  the  "  heads  "  are  the  gold-bearing  gravels  of  the  mountain- 
valley.  The  soft  is  separated  from  the  hard,  the  heavy  from 
the  light,  until  at  length  the  metal  once  incased  in  quartz  and 
enclosed  within  the  rock  is  set  free,  to  be  collected  wherever 
the  eager  stream  has  so  abated  its  force  as  to  permit  the  parti- 
cles of  gold  to  find  a  quiet  resting-place. 

It  is  a  great  sifting-process.  The  motion  of  the  water  is  gov- 
erned by  the  slope  of  the  surface.  In  a  flat  country  the  condi- 
tions resemble  those  surrounding  a  mill  so  situated  as  to  be  in- 
capable of  getting  rid  of  its  accumulating  tailings.  Should  the 
water-supply  of  the  mill  also  prove  insufficient  to  carry  out  its 
operations,  then  the  analogy  with  a  desert  plateau  is  complete. 
The  process  of  concentration  must  in  both  cases  remain  un- 
finished. 

The  gold-bearing  gravels  of  California  and  Victoria,  for 
example,  usually  rest  on  a  hard  bed-rock,  whose  water-worn 
surface  speaks  of  the  agency  which  made  it  so.  The  particles 
of  gold  and  heavy  iron-sand  have  been  washed  clean ;  the  over- 
lying pebbles  and  quartz  gravel  are  comparatively  free  from 
material  less  resisting  than  themselves ;  and,  if  there  be  any  clay, 
it  is  found  in  distinct  layers,  in  positions  testifying  to  the  varia- 


10 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 


TABLE  I. — Meteorological  Conditions  at  Coolgardie,  1897. 


TEMPERATURE. 

TEMPERATURE 
OP  DEW-POINT. 

RAINFALL. 

Month. 

Mean 
Max. 

Mean 
Min. 

Highest 
Max. 

Lowest 
Min. 

Greatest 
Variation 
in  One  Day. 

Mean. 

9A.M.      3P.M. 

Total 
Inches. 

Days. 

0 

0 

0 

o 

0 

0 

o 

January  

94.1 

63.2 

104.3 

53.0 

42.2 

53.5 

54.0 

.56 

4 

February... 

89.4 

58.5 

104.6 

47.4 

47.3 

51.8 

53.6 

.54 

5 

March  

85.6 

57.7 

98.4 

50.0 

41.0 

49.2 

55.0 

.10 

2 

April 

81  2 

53  9 

96  1 

39  1 

36  5 

51  3 

57  4 

01 

^ 

May  

71.4 

46.6 

88.4 

38.2 

41.5 

46.9 

53.5 

.09 

3 

June  ...  . 

62  9 

43  9 

71  2 

31  5 

09  g 

44  2 

49  7 

1  04 

g 

July  

65.1 

42.4 

74.0 

36  5 

33  5 

43  5 

47  5 

34 

g 

August  

63.8 

41.5 

81.0 

33.0 

34.6 

40.8 

43.7 

1.08 

10 

September- 

75.0 

47.5 

92.0 

35.0 

39.7 

43.7 

49.5 

.29 

6 

October  

81.0 

49.8 

91.0 

41.0 

39.7 

.06 

2 

November- 

90.6 

58.4 

105.0 

47.3 

44  6 

09 

1 

December.. 

91.7 

59.5 

109.2 

ft!  0 

44  9 

1  31 

4 

1898. 

January  I    97.6 

65.1 

111.2 

64.0 

43.2 

60.1 

68.2 

Nil. 

February...     89.3 

62.5 

107.2 

48.0 

37.7 

57.0 

60.2 

.27 

1 

TABLE  II. — Meteorological  Conditions  at  Kalgoorlie,  1897. 


TEMPERATURE. 

TEMPERATURE 
OF  DEW-POINT. 

RAINFALL. 

Month. 

Mean 
Max. 

Mean 
Min. 

Highest 
Max. 

Lowest 
Min. 

Greatest 
Variation 
in  One  Day. 

Mean. 

9A.M.       3P.M. 

Total 
Inches. 

Days. 

o 

, 

„ 

0 

o 

0 

Q 

January  

92.9 

66.0 

105.0 

55.0 

34.2 

51.1 

52.0 

.38 

2 

February- 

88.2 

61.6 

103.0 

49.0 

34.7 

51.2 

51.5 

.02 

1 

March  

83.8 

58.9 

98.4 

51.0 

39.0 

49.0 

49.4 

.52 

6 

April  

80.0 

55.9 

95.4 

38.8 

K2.8 

48.0 

46.8 

.20 

1 

May  

69.8 

48.0 

88.1 

37.0 

40.4 

46.5 

45.0 

.10 

1 

June  

62.9 

47.4 

73.2 

36.2 

30.2 

46.4 

49.1 

1.26 

14 

July 

64.4 

43.3 

74.0 

33.2 

29.8 

42.8 

43.7 

3 

August  

63.8 

43.3 

82.0 

34.0 

29.1 

40.0 

41.7 

'65 

9 

September. 

74.2 

48.8 

90.8 

37.2 

40.2 

41.6 

43.8 

!41 

5 

October  

78.5 

51.8 

90.2 

41.0 

38.0 

42.0 

40.4 

.11 

2 

November- 

90.2 

59.0 

103.0 

48.0 

49.0 

46.8 

48.7 

.06 

1 

December.. 

90.7 

61.6 

109.2 

49.4 

39.0 

48.3 

49.5 

.82 

4 

1898. 

January  

98.0 

66.8 

113.2 

55.0 

41.0 

51.3 

50.3 

.02 

1 

February... 

90.5 

63.4 

109.8 

48.2 

38.6 

51.2 

49.9 

.36 

3 

tions  in  the  velocity  and  volume  of  the  stream  which  laid  down 
the  deposit  as  a  whole.  It  is  an  orderly  arrangement  of  assorted 
material. 

Compare  with  this  the  alluvium  of  the  desert.  A  low  ridge 
is  crested  with  the  outcrop  of  a  gold-bearing  quartz-vein  which, 
amid  that  surrounding  sea  of  dark-blue  scrub,  justifies  its  colo- 
nial designation,  a  "reef."  On  its  flanks  there  is  a  thin  cover  of 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  11 

sandy  soil  which  gradually  thickens,  a  little  lower  down  the 
slope,  to  a  deposit  of  several  feet.  Sink  a  hole  and  you  will 
find,  first  an  inch  or  two  of  loose  sand  and  dust,  then  a  more 
solid  layer  of  gravel  and  dirt,  which  in  turn  passes  imperceptibly 
into  a  compact  material  consisting  of  fragments  of  rock  and 
quartz,  held  firmly  together  by  clay.  It  is  called  "  cement," 
and  it  might  better  be  termed  an  "  agglomerate."  It  is  an  un- 
classified product  of  erosion,  and  lies  close  to  the  place  of  its 
origin,  as  a  mere  collection  of  unsorted  debris. 

The  rock  on  which  the  deposit  rests  is  so  softened  by  decom- 
position that  it  is  frequently  taken  for  a  part  of  the  overlying 
detritus.  If  the  hole  be  continued  so  as  to  become  a  well  or 
shaft,  it  will  penetrate  through  additional  oxidized  ground  until 
this  suddenly  gives  place  to  diorite  or  granite  (the  two  prevail- 
ing formations)  at  a  depth  varying  from  75  to  200  feet,  which 
is  the  drainage-level  of  the  region. 

This  deposit  owes  its  existence  to  the  wind  and  rain,  assisted 
by  gravity  acting  on  a  slightly  inclined  surface.  Wind  is  ordi- 
narily an  insignificant  geological  agent,  but  in  the  constant  and 
violent  draughts  of  a  high  plateau  there  is  a  force  which,  work- 
ing during  long  periods  of  time,  is  capable  of  producing  notable 
results.  In  the  vicinity  of  Coolgardie  and  Kalgoorlie,  espe- 
cially the  latter,  which  has  the  less  broken  topography,  the 
dust-storms  are  almost  ceaseless,  and  bear  forceful  testimony  to 
the  amount  of  material  which  can  be  conveyed  in  the  air.  The 
wind  careers  over  the  country  in  gyrating  whirls,  to  which  the 
aborigines  give  the  name  of  "  willy-willy,"  nor  have  the  white 
invaders  ventured  to  call  them  otherwise ;  and  as  these  whirl- 
winds go  waltzing  across  the  wretched  town,  they  gather  up  in 
their  skirts  all  the  scattered  refuse  of  a  border  civilization.  I 
formed  the  impression  that  the  wind  had  a  prevailing  direction 
from  the  southeast  to  the  northwest,  that  is,  from  the  nearest 
sea  toward  the  heated  interior;  but  the  meteorological  re- 
ports of  the  government  do  not  confirm  this  supposition.  In 
the  accompanying  table,  Beaufort's  scale  of  wind-force  is  em- 
ployed. It  will  be  observed  that  the  meteorological  reports 
confirm  the  impression  that  Kalgoorlie  is  more  windy  than 
Coolgardie,  and  that  a  quiet  condition  of  the  atmosphere  is  un- 
usual in  both  districts.  Nor  is  there  any  consistency  of  direc- 
tion, as  is  proved  by  the  observations  made,  for  example,  at 


12 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 


Kalgoorlie  during  the  month  of  September,  1897.  It  is  evi- 
dent that  the  wind  blew  where  it  listed,  and  no  man  could  tell 
whence  it  came.  The  following  is  Beaufort's  scale  of  wind- 
force  : 

Speed  of  wind 
Number.  '  Description.  in  miles  per  hour. 

0  Calm.  3 

1  Light  air.  8 

2  Light  breeze.  13 

3  Gentle  breeze.  18 

4  Moderate  breeze.  23 

5  Fre-h  breeze.  28 

6  Strong  breeze.  34 

7  Moderate  gale.  40 

8  Fresh  gale.  48 

9  Strong  gale.  56 

10  Whole  gale.  65 

11  Storm.  75 

12  Hurricane.  90 


TABLE  ILL— Wind-Force,  1897. 


Month. 

COOLGARDIE. 

KALGOORLIE. 

9  A.M. 

Max.       Min. 

3P.M. 
Max.       Min. 

9  A.M. 

Max.       Min. 

3  P.M. 
Max.       Min. 

January 

3 
4 
3 

4 
8 
2 
5 
5 
9 
5 
6 
9 

1 
2 
2 
0 

2 
1 

1 

3 
4 
3 
3 
3 
3 
6 
6 
9 
8 
9 
4 

0 
1 

1 
2 
0 
2 
1 
1 
1 
1 
1 
1 

2 
7 
5 

2 
5 
9 
3 
6 
6 
7 
5 
2 

1 

2 
2 
1 
2 
2 
2 
2 

2 
2 
2 
2 

3 

7 
2 
9 
2 
5 
4 
8 
9 
6 
8 
3 

3 
2 

0 
1 

2 

2 

2 
2 
2 
2 
2 
2 

February 

March 

May  

June  

July  

August  

September  . 

October 

November   . 

December  

TABLE  IV. —  Variation  in  Direction  of  the  Wind  at 
Kalgoorlie  during  September •,  1897. 


9  A.M. 


Direction  of  wind. 

N. 

N.  to  E. 

E. 
S.  to  E. 

S. 
S.  to  W. 

w. 

N.  to  W. 


Days. 
4 

5 
3 
5 
1 
6 
1 
2 


3  P.M. 

Direction  of  wind.         Days. 
4 


N. 
N.  to  E. 

E. 
S.  to  E. 

S. 
S.  to  W. 

w. 

N.  to  W. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  13 

Observations  such  as  have  been  quoted  in  Tables  III.  and  IV. 
necessarily  fail  to  record  the  really  characteristic  play  of  the 
wind  in  this  region.  The  whirl-storms,  referred  to  already, 
spring  up  suddenly,  rush  madly  across  the  plain,  suck  up  every- 
thing lying  loose  on  the  surface,  arid  as  suddenly  subside. 
These  apparently  erratic  air-disturbances  are  responsible  for  the 
transport  of  the  greater  part  of  the  material  which  weathering 
and  erosion  have  disintegrated.  So  far  as  I  know,  measure- 
ments of  the  transporting-power  of  the  wind  have  not  been  made 
in  this  particular  region ;  but  elsewhere  in  Australia  scattered 
observations  have  been  made ;  for  example,  that  fences  4  feet 
high  are  buried  by  drifting  sand  in  a  period  only  slightly  ex- 
ceeding two  years.  In  the  Libyan  desert,  bordering  the  Kile 
valley,  the  same  results  can  be  seen.  Thus,  for  instance,  the 
sand-storms  bury  the  temple  of  the  Sphinx  every  summer,  and 
the  road  built  by  Ismail  Pasha,  from  the  Mena  House  to  the 
Pyramids,  is  filled  with  sand  up  to  the  level  of  the  6-foot  para- 
pet in  less  than  ten  days.* 

In  West  Australia  there  is  much  evidence  of  that  which 
geologists  euphuistically  term  the  ^Eolian  agency.  The  wind 
has  been  stirring  and  sifting  the  material  lying  loose  on  the 
surface  until  it  has  become  classified  to  a  remarkable  degree. 
In  traveling  over  the  country,  one  is  soon  called  upon  to  notice 
the  broken  white  quartz  scattered  over  the  ground,  in  big 
patches  many  acres  wide.  These  alternate  with  stretches, 
steel-gray  in  the  morning  and  blue-black  toward  the  close  of 
day,  of  ironstone  fragments.  Leave  the  trail ;  go  a  short  distance 
into  the  bush ;  and  you  will  find  the  surface  covered  with  dust 
in  which  each  step  leaves  an  evident  footprint.  It  is  the  veri- 
table dust  of  ages,  not  the  earth-smoke  blown  from  man's  restless 
to-and-fro.  The  wind  has  sorted  the  quartz,  the  ironstone 
and  the  dust.  The  latter  has  been  scattered  in  contemptuous 
carelessness  all  over  the  face  of  the  weary  desolation,  but  the 
heavy  ironstone  remains  not  far  from  where  it  was  broken  off 
the  decomposing  diorite  until,  shattered  and  comminuted  to 
powder,  it  also  is  winnowed  by  the  dust-storm.  The  numerous 
veins,  large  and  small,  traversing  the  country  have  contributed 
the  quartz  which  the  wind  has  collected,  so  that  it  sometimes 
covers  the  ground  with  the  glittering  whiteness  of  a  snow-drift. 

*  So  my  dragoman  informed  me  when  I  was  there  last  February. 


14  THE    ALLUVIAL    DEPOSITS    OF    WESTERN   AUSTRALIA. 

From  these  stretches  of  ironstone  and  quartz  one  would 
naturally  infer  the  occurrence,  somewhere  underneath  the 
surface,  of  large  masses  of  both.  Owing  to  the  extreme  slow- 
ness with  which  denudation  progresses  in  this  arid  region,  and 
the  consequent  very  gradual  lowering  of  the  zone  of  oxida- 
tion, the  rocks  exhibit,  above  the  drainage-level,  a  marked  in- 
tensity of  chemical  action.  The  granite  is  kaolinized  to  an 
almost  incoherent  clay,  and  the  diorite  is  rendered  abnormally 
heavy  in  iron  by  the  surface-concentration  of  decomposition-prod- 
ucts. And,  as  the  rock  is  eroded,  the  quartz,  on  account  of  its 
hardness,  persists,  so  that  a  series  of  small  stringers  eventually 
yields  an  accumulation  suggestive  of  its  derivation  from  a  large 
mass.  It  is  a  process  of  concentration  which,  there  is  reason  to 
believe,  has  also  affected  the  gold-occurrence,  the  upper  por- 
tions of  veins  being  enriched  by  the  deposition  of  the  gold  left 
behind  from  lode-matter  which  was  long  ago  disintegrated  and 
removed  by  erosion. 

If  we  now  turn  to  the  "  dry-blower  "  and  watch  him  at  his 
work  we  shall  see  the  same  processes  utilized  in  the  winnowing 
of  the  gold. 

III. — DRY-BLOWING. 

In  West  Australia  the  absence  of  running  water  renders  un- 
available the  cradle  and  the  sluice-box  of  ordinary  placer- 
mining,  with  the  result  that  the  prospector  has  learnt,  intui- 
tively, to  utilize  the  agency  which  he  sees  incessantly  at  work 
in  the  nature  around  him.  Wind  replaces  water.  The  method 
is  simple.  Taking  two  pans,*  he  places  one  of  them  on  the 
ground,  empty,  while  into  the  other  he  puts  a  shovelful  of  the 
"  dirt,"  that  is,  the  sandy  detritus  containing  the  gold.  The 
material  is  shaken  up  so  as  to  bring  the  big  lumps  on  top,  and 
then,  resting  the  pan  on  one  knee  and  holding  it  with  his  left 
hand  he  uses  the  right  hand  to  skim  off  the  coarse  particles  (as 
shown  in  Fig.  5).  Then  standing  erect  and  facing  at  right  angles 
to  the  direction  of  the  wind,  he  slowly  empties  the  full  pan  into 
the  empty  one  at  his  feet  (see  Fig.  6).  As  the  stream  of  dry 
dirt  falls,  the  wind  selects  the  fine  and  blows  it  in  a  cloud  of 
dust  to  leeward.  The  operation  is  then  reversed,  the  pan 
which  has  just  been  emptied  being  placed  on  the  ground  so  as 

*  The  Australian  calls  them  u  dishes.1' 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  15 

to  receive  the  contents  of  the  other.  This  is  repeated  three  or 
four  times,  according  to  the  degree  of  concentration  effected. 
In  a  strong  breeze  one  operation  may  prove  sufficient.  To  pre- 
vent the  loss  of  the  fine  gold  which  is  sometimes  carried  away 
with  the  dust  it  is  customary  to  spread  a  piece  of  canvas  on  the 
ground,  one  end  being  placed  under  the  pan  and  the  other  ex- 
tending to  leeward.*  The  next  stage  is  to  further  winnow  the 
material  by  tossing  it  up  and  down  in  the  pan  (see  Fig.  7) ; 
the  latter  is  held  slanting  forward,  and  is  jerked  so  as  to  throw 
the  dirt  from  the  front  to  the  back  of  the  pan.  The  light 
particles  are  separated,  as  chaff  is  driven  from  grain.  Then, 
giving  the  dish  a  vanning  movement,  the  prospector  again  re- 
moves the  coarser  particles  that  come  to  the  surface  by  skim- 
ming them  off  with  his  hand.  There  now  remains  about  half 
a  pint  of  material,  and  this  is  diminished  by  panning,  just  as 
in  water,  the  dry  particles  having  a  mobility  permitting  this 
method  of  treatment.  Finally  he  drops  on  his  knee,  and,  hold- 
ing the  pan  (see  Fig.  8)  so  that  it  is  tilted  forward,  he  raises 
it  up  to  his  mouth  and  uses  the  breath  of  his  lungs  to  complete 
the  process.  The  particles  of  gold  are  seen  fringing  the  edge 
of  the  iron  sand.  If  the  yield  consist  of  only  a  few  minute  par- 
ticles,f  he  puts  his  moist  thumb  on  them,  and  so  transfers  them 
to  his  pocket;  but  if  there  be  any  coarse  pieces — nuggets — 
they  are  put  into  the  leather  wallet  attached  to  his  belt. 

In  watching  a  dry-blower  at  work,  it  becomes  evident 
that  the  operation,  like  every  process  of  concentration  when 
properly  conducted,  consists  of  sizing  and  classification.  The 
wind  removes  the  fine  sand  and  the  dust,  the  operator's  hand 
skims  off  the  larger  lumps  of  dirt,  so  that  there  finally  remains 
a  collection  of  those  heavy  particles  of  ironstone  which,  as  in 
ordinary  placer-mining,  accompany  the  gold. 

Owing  to  the  perfect  dryness  of  the  dirt  and  the  heat  im- 
parted to  the  surface  of  the  iron  pan  under  a  tropical  sun,  the 
material  behaves  with  much  of  the  mobility  which  it  would 
have  if  water  and  not  air  were  the  vehicle  employed.  It  re- 
minds one  of  the  behavior  of  a  charge  in  the  roasting-furnace, 
in  which  the  hot  air  cushions  each  particle  so  as  to  give  to  the 
mass  an  apparent  fluidity. 

*  As  illustrated  in  the  Figs.  5,  6,  7,  and  8.     These  were  reproduced  by  Mr. 
Henry  Keed,  of  Denver,  from  photographs  taken  by  me  at  Kalgoorlie. 
f  "  A  few  small  colors,"  as  we  would  put  it  in  the  United  States. 


16  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

The  rapidity  and  completeness  of  the  operation  depend  on 
the  strength  and  uniformity  of  the  wind.  There  is  a  constant 
light  breeze  on  the  gold-fields,  even  during  those  happy  inter- 
vals when  the  dust-whirls  have  temporarily  subsided ;  but  the 
cloudy  mornings  of  the  wet  season  and  the  sultry  days  of  the 
hottest  summer  months  are  alike  unfavorable  to  dry-blowing, 
because  at  such  times  the  air  is  dead.  Many  of  the  mining- 
camps  are  situated  on  a  slight  rise  of  ground,  overlooking  those 
desolate  sinks  of  salt  and  sand  which  are  called  "lakes;"  and 
the  difference  of  level  is  marked  by  a  constant  breeze  which  is 
a  good  friend  to  the  dry-blower. 

In  the  history  of  ordinary  alluvial  mining,  washing  with  the 
pan  was  succeeded  by  the  use  of  the  sluice-box  and  the  cradle. 
Similarly  the  "  dishes  "  of  the  dry-blower  are  replaced  by  ma- 
chine's of  several  types,  all  of  which,  however,  are  based  on  the 
idea  of  a  shaking  movement  in  the  presence  of  a  current  of  air. 
The  simplest  contrivance  is  represented  in  Fig.  9.  This  machine 
is  2  feet  wide  and  4  feet  long.  A  is  a  hopper  with  a  sheet-iron 
bottom  punched  with  1-inch  holes,  B  is  a  12-mesh  screen,  C  is 
an  18-mesh  screen,  and  D  is  the  final  product  of  the  operation. 
The  dry-blower  empties  a  shovelful  of  dirt  into  the  hopper, 
places  his  hands  on  the  two  sides  of  the  machine  and  shakes  it 
from  side  to*  side.  There  is  sufficient  play  in  the  frame  itself 
to  permit  a  movement  which  causes  the  material  to  pass 
through  the  series  "of  screens  and  accumulate  underneath.  It 
is  then  treated  by  hand,  as  previously  described  and  illustrated. 
One  man  will  put  through  about  5  tons  of  loose  dirt  in  a  work- 
ing-day of  seven  hours. 

Another  and  more  elaborate  contrivance  is  exhibited  in  Fig. 
10.  It  consists  of  a  series  of  four  trays,  hung  on  a  triangular 
frame,  B  C  D.  The  trays  are  22  inches  in  diameter.  They  are 
comparatively  flat  and  have  screen-bottoms,  through  the  center 
of  which  an  iron  rod  passes  to  the  eccentric,  G,  which  receives 
the  required  movement  through  the  lever  A  E  F,  of  which  A  is 
the  handle.  The  trays  are  5  inches  apart  and  are  held  in  place 
by  wires,  H  H.  The  material  to  be  treated  is  placed  in  the 
uppermost  tray,  which  is  a  hopper  pierced  with  inch-holes. 
No.  2  has  f  holes,  No.  3  has  a  10-mesh  screen  and  No.  4  has 
an  18-mesh  screen.  The  lowest,  No.  5,  is  flat  and  serves  as  a 
receptacle  for  the  final  product,  which  is  dry-blown  by  hand,  as 
heretofore  described. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA. 


17 


18  THE   ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA, 


THE    ALLUVIAL   DEPOSITS    OF   WESTERN   AUSTRALIA.  19 


20  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

FIG.  5. 


Dry-blower  at  Work. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  21 

FIG.  6. 


Dry-blower  at  Work. 


22  THE   ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA. 

FIG.  7. 


Drv  blower  at  Work. 


THE   ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  23 

FIG.  8. 


Drv-blower  at  Work. 


24  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

FIG.  9. 

!*&• 


DRY   BLOWING  MACHINE 


DRY   BLOWING  MACHINE 


PLAN   OF  TRAY 


THE   ALLUVIAL    DEPOSITS    OF   WESTERN   AtJSTRALlA.  25 


- 


26  THE   ALLUVIAL    DEPOSITS    OF   WESTERN   AUSTRALIA. 


FIG.  12. 


DRY   BLOWERS  AT  WORK 


FIG.  13. 


Lorden's  Dry -blowing  Machine. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  27 


28  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  29 


4 


4-    -•-     •+    pnn    irrn 
"1"      "*"       N    b-J 


+       4  1 

+       4-        +       Q          0 


30  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

FIG.  18. 


Horiz.ontal  Plane 


0     »     4     6     8     10   12    14    16   18    'A> 


CEMENT  DEPOSIT,  KINTORE,   WEST  AUSTRALIA 
FlO.    19. 


Shaft  Shaft 


Longitudinal  Section 

Hole       Shaft  Shaft 


THE   CEMENT  DEPOSIT  AT   KANOWNA 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA. 


31 


CO 


XX 

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3    -3 

° 


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".io.      '.      •»*•"*•••••    J   ......      .•..*. 


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32 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 


I 


•*•.•;.•.•:••:::'  'V  •••••••    •  •  •'•  *•*'•  ^,-  «    Vl^'  •')    ~~ 

^sl^(^  ^-^^^s 

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THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  33 

In  these  two  contrivances  no  attempt  is  made  to  supple- 
ment the  wind  by  an  artificial  air-current.  The  next  step  is 
to  use  a  bellows.  Fig.  11  shows  such  an  arrangement.  It 
consists  of  a  hopper  A  and  a  series  of  screens,  B,  E,  F,  G  and 
H.  By  turning  the  handle  M  the  disk  K  is  revolved;  and  this, 
by  means  of  a  belt,  transmits  its  movement  to  the  pulley,  which 
shakes  the  screen  B  B  through  the  eccentric-rod  C,  and  at  the 
same  time  operates  the  bellows  D  through  the  disk  K.  Fig.  12 
illustrates  the  machine  when  in  operation. 

When  the  material  is  placed  in  the  hopper  A  and  the  ma- 
chine is  set  in  motion,  the  large  lumps  run  off  over  the  grizzly 
or  sizing-screen  B  B,  the  upper  part  of  which  is  made  of  par- 
allel wires  ^-inch  apart,  and  the  lower  portion  of  8-mesh.  The 
finer  stuff  falls  down  into  the  shoots  C  C  and  E  E,  respectively, 
and  reaches  F,  which  is  another  (12-mesh)  screen,  supplied  also 
with  riffles.  As  it  descends  through  the  screens  at  G  and  H, 
both  1 8-mesh,  the  blast  from  the  bellows  keeps  the  material  in 
agitation,  and  aids  the  requisite  separation  between  the  particles 
of  gold  and  the  dust.  The  final  product  is  panned  by  hand. 

One  of  the  most  popular  dry-blowing  machines  is  that  made 
by  Steve  Lorden,  at  Freeman  tie.  It  is  illustrated  in  Fig.  13. 
The  essential  parts  are  : 

A.  Feed-hopper,  sheet-iron  bottom,  punched  with  inch-holes, 
hinged  at  A2  and  provided  with  riffles  A3,  which  arrest  the 
heavier  particles  of  gold,  while  the  coarse  lumps  of  dirt  pass  out 
of  the  machine  over  the  shoot  B2  and  the  fine  stuff  falls  through 
into 

B.  Second  hopper,  which  has  riffles  and  smaller  perforations, 
repeating  the  process.     To  examine  this  hopper,  the  upper  one, 
A,  is  sprung  out  of  position  at  A4. 

C.  C.  Return-shoots  which  lead  the  reduced  material  for  fur- 
ther sizing  upon  the  sloping  screen  E,  which  also  has  a  series  of 
riffles,  and  is  placed  directly  over  the  air-chamber  F. 

D2  is  a  discharge-shoot  for  the  screen  E.  G,  G  are  air-chan- 
nels from  the  bellows  H,  H. 

H,  H.  Double  blast-bellows,  one  on  each  side,  which  ride  on 
carriers  H2,  so  arranged  as  to  give  the  requisite  play  and  to  re- 
lieve the  bellows  from  undue  strain  when  in  operation. 

I,  I.  Rockers,  bolted  firmly  to  two  foundation-blocks,  Lj, 
which  form  the  stand,  the  only  part  of  the  machine  that  is  not 

3 


34  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

in  motion.    The  curve  of  the  rockers  allows  all  dirt  to  fall  away 
from  the  pivot-pins  J,  J,  by  which  the  apparatus  swings. 

K,  K.  Standards,  hinged  at  L,  so  that  the  machine  folds 
up,  as  shown  in  Fig.  14. 

M,  M.  Brackets  for  the  insertion  of  two  poles,  by  means  of 
which  a  couple  of  men  can  carry  the  machine  conveniently. 

The  operator  holds  one  handle,  at  A4,  in  each  hand  and 
rocks  the  machine,  this  serving  simultaneously  to  put  the  bel- 
lows, hopper  and  screens  all  into  movement.  The  machine 
weighs  124  pounds  and  has  a  capacity  of  from  10  to  14  loads 
(a  load  is  roughly  one  ton)  per  day.  The  price  at  Freemantle 
is  £16  or  about  $80. 

The  deposits  exploited  by  the  aid  of  these  machines  (see  Fig. 
15)  are  of  a  generally  patchy  character  and  lie  at  the  upper 
ends  of  the  depressions  formed  where  the  surface  slopes  away 
from  ridges  traversed  by  the  veins  of  gold-bearing  quartz. 
The  prospector  has  an  eye  for  the  contour  of  the  ground,  and 
looks  for  the  point  where  the  rock-surface  disappears  under  the 
fragmentary  overburden  which  he  calls  "  made  ground  "  as  dis- 
tinguished from  the  underlying  "  bed-rock."  In  his  search  he 
is  usually  guided  by  seeing  the  outcrop  of  quartz,  marking  a 
possible  source  of  detrital  gold,  and  by  the  actual  finding  of 
specimens  on  the  surface. 

The  distribution  of  the  gold  in  these  deposits  reminds  one  of 
its  position  on  a  vanning-shovel.  It  may  be  traced  up  to  the  out- 
crop which  yielded  it,  or  it  may  be  scattered  in  the  sand  for  half 
a  mile;  but  the  rich  and  only  workable  part  of  the  deposit  will 
ordinarily  be  found  at  a  distance  of  30  or  40  feet  from  the  reef. 

Underneath  these  patches  of  superficial  gold-bearing  detritus 
there  are  found  partially  consolidated  accumulations,  which  are 
more  extensive  and,  quite  apart  from  their  greater  economic 
value,  are  also  of  superior  interest,  because  of  their  better-de- 
fined geological  features. 

IV. — THE  CEMENT-DEPOSITS. 

In  the  ordinary  course  of  professional  work  I  examined  the 
two  most  important  of  these  deposits,  at  Kintore  and  Kanowna, 
respectively.  Since  then  a  third  formation  of  a  similar  char- 
acter has  been  opened  up,  also  at  Kanowna.  This  I  happened 
to  see  when  in  the  stages  of  early  development,  and  before  it 
had  been  extensively  exploited. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  35 

The  deposit  of  cement  at  Kintore  was  one  of  the  earliest 
worked.  It  is  situated  23  miles  northwest  of  Coolgardie,  on 
the  road  to  Menzies.  The  West  Australian  Proprietary  Cement 
Company  mined  the  ground  with  a  success  which  was  short- 
lived, because  of  the  restricted  quantity  of  material  rich  enough 
to  pay  the  high  costs  of  treatment.  In  four  months,  7335 
ounces  of  gold  were  obtained  by  treating  4115  tons  in  a  stamp- 
mill,  supplemented  by  cyanide- vats. 

Enough  work  has  been  done  to  disclose  the  character  of  the 
deposit.  Figs.  16  and  17  are  representative  sections  obtained 
in  the  open  cuts.  Under  a  thin  covering  of  sand  and  dust  there 
occurs  a  bed  of  kaolin,  ranging  from  a  couple  of  inches  to  a 
foot  in  thickness ;  and  this  overlies  from  15  inches  to  2  feet  of 
"  sand-rock,"  which  in  turn  gives  place  to  the  gold-bearing 
cement,  which  has  an  average  thickness  of  2J  feet.  The  last 
lies  directly  upon  an  irregular  surface  of  decomposed  granite. 

The  several  layers  composing  the  deposit  are  separated  by 
seams  of  pipe-clay,  which,  like  the  kaolin,  are  simply  the  pro- 
duct of  the  decomposition  of  the  constituents  of  the  granite, 
particularly  the  feldspar.  The  sand-rock  may  be  described  as  a 
coarse,  incompletely  consolidated  sandstone  or  grit,  consisting 
mainly  of  iron-stained  particles  of  quartz,  loosely  cemented. 
The  cement  has  a  bluish-gray  tinge,  owing  to  the  play  of  light 
on  the  quartz  fragments.  This,  too,  is  not  quite  compacted, 
since  fractures  through  the  material  do  not  break  across  the 
pebbles,  which  are  harder  than  the  clay  binding  them  together. 
In  this  respect  the  cement  differs,  for  example,  from  the  South 
African  "banket,"  to  which  it  has  been  compared.  From  a 
distance,  the  cement  looks  like  a  coarse  sandstone  and  exhibits 
a  rough-joint  structure.  The  materials  of  which  it  has  been 
made  up  have  undergone  incipient  sizing,  so  that  different 
layers  of  varying  coarseness  are  distinguishable. 

The  bed-rock  is  granite,  so  softened  by  decomposition  as  to 
be  mistaken  by  the  miners  for  a  part  of  the  alluvial  deposit. 
It  is  kaolinized  to  a  depth  which  the  neighboring  mine-shafts 
prove  to  reach  a  maximum  of  130  feet.  The  surface  on  which 
the  cement  lies  is  marked  by  pot-holes  having  a  maximum 
depth  of  2  feet  and  a  diameter  reaching  to  3  feet.  These  holes 
are  filled  with  cement,  which  is  usually  poor  save  at  the  rims, 
where  some  of  the  richest  mill-stuff  has  been  obtained. 

All  the  members  of  the  deposit,  from  surface  to  bed-rock, 


36  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

contain  some  gold,  the  kaolin  being  the  poorest.  The  cement 
j.tself  attains  a  maximum  thickness  of  5  feet.  The  richest  parts 
occur  in  lateral  embranchments  from  the  main  body  of  the 
deposit.  The  kaolin  has  become  hardened  and  dried.  It 
breaks  like  shale;  and  its  true  character  is  obscured  by  the 
down-filtering  of  red  sand  through  cracks  reaching  to  the  soil 
overhead. 

The  deposit  extends  through  a  number  of  mining  claims,  as 
shown  on  the  accompanying  map  (Fig.  18).  It  has  been  traced 
for  a  length  of  three-quarters  of  a  mile.  At  the  east  end  it 
begins  as  a  narrow  neck  about  15  feet  wide,  and  then  enlarges 
steadily  to  100  feet.  Occasional  bulges  increase  this  width  to 
a  maximum  of  250  feet.  At  the  edge  it  gives  place,  as  it  thins 
out,  to  2  or  3  feet  of  ironstone  gravel,  carrying  3  or  4  dwts.  of 
gold  per  ton.  The  best  part,  economically,  of  the  deposit  lies 
in  the  Ophelia  and  Hilton  claims,  which,  it  will  be  noted,  are 
situated  at  the  lower  end  of  the  basin. 

The  bed-rock  rises  westward  at  the  rate  of  15  feet  per 
thousand.  This  fact  suggested  that  the  origin  of  the  gold-bear- 
ing cement  was  to  be  found  in  the  reefs  which  were  being  profit- 
ably mined  by  the  Sugar  Loaf  Company.  The  workings  were 
136  feet  deep  at  the  time  of  my  visit  in  September,  1897.  The 
veins  traverse  granite  which  has  been  kaolinized  to  130  feet 
from  the  surface.  They  consist  of  white  quartz  and  are  narrow 
(4  to  12  inches),  but  they  carry  short  shoots  of  very  high-grade 
(3  to  10  ounces  of  gold  per  ton)  ore.  The  gold  occurs  native,  in 
flakes  penetrating  the  cleavage-planes  of  the  quartz  like  a  golden 
mosaic,  and  also  in  coarser  particles,  which,  under  closer  exam- 
ination, prove  to  be  octahedral  crystals  with  curiously  rounded 
edges.  A  comparison  of  these  veins  and  their  enclosing  rock 
with  the  material  composing  the  cement-deposit  unquestion- 
ably indicates  the  derivation  of  the  latter  from  the  former. 
The  cement  carries  gold  which  is  exactly  similar  to  that  seen  in 
the  reefs;  the  quartz  fragments  in  the  alluvial  are  identical 
with  the  stone  broken  in  the  Sugar  Loaf  mine.  Samples  of 
both  lie  before  me  as  I  write,  emphasizing  the  conclusion  just 
stated.  In  the  cement  occur  particles  of  quartz  showing 
gold.  The  loose  gold  in  the  cement  has  been  but  slightly  worn, 
and  the  quartz  pieces  are  rather  subangular  than  rounded,  so 
that  they  can  hardly  be  termed  "pebbles;"  and  the  deposit 
itself  is  better  defined  as  an  agglomerate  than  as  a  conglomerate. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  37 

The  binding-material,  the  overlying  layer  of  kaolin  and  the 
sand-rock  capping  the  gold-bearing  stratum  of  cement,  all  ex- 
hibit very  clearly  their  derivation  from  a  decomposed  granite, 
similar  to  that  which  encloses  the  reefs  and  forms  the  bed-rock 
of  the  alluvium  itself. 

The  topography  confirms  this  supposed  relationship.  The 
highest  point  along  the  major  axis  of  the  cement-deposit  is  a 
very  low  ridge  separating  the  workings  of  the  Sugar  Loaf  from 
the  alluvial  ground.  The  house  of  the  manager  of  the  Sugar 
Loaf  is  on  this  divide.  The  reefs  are  462  feet  westward,  and 
only  15  feet  lower  where  they  appear  at  the  surface.  The  ce- 
ment deposit  begins  on  the  Great  Dyke  lease,  at  a  point  530  feet 
eastward,  and  only  8  feet  lower.  The  cement  then  extends 
on  a  gentle  down-slope  of  15  feet  per  thousand  for  a  distance  of 
3600  feet* 

It  occupies  a  very  shallow  depression,  and  in  its  structure 
bears  internal  evidence  of  considerable  geological  age,  suggest- 
ing that  it  was  formed  at  a  time  when  the  Sugar  Loaf  reefs 
reached  the  surface  at  a  level  superior  to  the  slight  ridge  now 
separating  them.  Reference  to  the  map  and  longitudinal  section 
(Fig.  18)  will  aid  the  above  description. 

Another  deposit  of  similar  character  has  been  explored  at 
Kanowna,  25  miles  northeast  of  Kalgoorlie,  and  about  60  miles 
east  of  the  locality  just  described. 

The  discovery  was  made  in  1893.  Eadh  digger  secured  a 
claim  50  feet  square,  and  sunk  a  shaft  to  the  gold-bearing 
cement  which  the  dry -blowers  had  uncovered  in  the  course  of 
their  prospecting.  The  deposit  became  in  due  time  "gophered" 
with  holes  and  shafts,  so  that  the  boundaries  of  the  cement  were 
accurately  determined.  In  1895  an  English  company  secured 
the  property  and  consolidated  the  claims  into  larger  leases. 
The  expectations  held  out  freely  by  responsible  engineers  that 
an  extremely  profitable  enterprise  could  be  based  on  the  rem- 
nants of  gold-bearing  ground  were  wholly  dissipated  in  the  suc- 
ceeding two  years.f 

The  deposit  lies  in  a  shallow  trough,  the  longer  axis  lying 

*  I  am  indebted  to  the  courtesy  of  Mr.  Alexander  Brand  and  Mr.  T.  G.  Paisley, 
the  managers  of  the  two  companies,  for  the  measurements  quoted. 

f  A  gross  blunder  was  made,  simply  through  insufficient  and  unsystematic 
sampling. 


38  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

east  and  west.  The  body  of  gold-bearing  cement  has  a  length 
of  about  700  feet  and  a  maximum  width  of  105  feet  (see  Fig. 
19).  Vertical  sections  exhibit  an  overburden  of  sandy  loam, 
from  a  few  inches  to  2J  feet  thick.  This  was  the  material 
worked  by  the  dry-blowers.  Then  comes  a  layer  of  detritus, 
called  "  wash  "  by  the  miners,  composed  of  fragments  of  iron- 
stone and  quartz  imbedded  in  clay,  and  reaching  to  a  maximum 
of  25  feet  from  the  surface.  This  overlies  the  cement  itself,  6 
inches  to  5  feet  thick,  and  easily  distinguished  from  its  roof  of 
detritus  and  its  floor  of  clay.  The  cement  consists  of  particles 
of  quartz  in  a  greenish  clay.  Near  the  rim  of  the  trough  the 
quartz  occurs  in  larger  and  more  angular  pieces.  .A  typical 
section,  obtained  from  a  pillar  in  the  old  workings,  is  given 
in  Fig.  20. 

The  gold-contents  are  irregular.  The  whole  body  of  cement 
probably  averaged  one  ounce  per  ton ;  but  only  the  richest  parts 
were  worked,  and  these  carried  many  ounces  to  the  ton;  so  that 
the  remnants  now  accessible  average,  from  the  surface  down, 
about  3J  dwts.*  The  clay  carries  2  dwts.  per  ton.  The  material 
was  treated  at  neighboring  stamp-mills. 

When  the  neighboring  mines,  the  White  Feather  Reward 
and  the  White  Feather  Main  Reef,  were  visited,  it  seemed  as 
natural  to  deduce  this  cement-deposit  from  the  erosion  of  gold- 
bearing  quartz-veins  as  it  had  been  to  relate  the  Sugar  Loaf 
reefs  at  Kintore  with  the  deposit  worked  by  the  West  Austra- 
lian Proprietary  Cement  Company.  Further  investigation  con- 
firmed this  inference. 

The  McAulifte  vein  (worked  by  the  W.  F.  Reward  mine) 
and  the  Main  Reef  (worked  by  the  W.  F.  Main  Reef  mine) 
traverse  diorite  at  or  near  the  line  where  large  dikes  of  granite 
porphyry  penetrate.  The  two  reefs  are  probably  identical,  and 
have  a  strike  which  takes  them  right  across  the  longer  axis  of 
the  cement-deposit  at.  a  point  near  the  head  of  the  trough  in 
which  it  lies  (see  map,  Fig.  19).  A  shaft  recently  sunk  to  a 
depth  of  200  feet  by  the  Golden  Cement  Company,  at  a  point 
marked  A,  reached  this  reef  by  means  of  a  crosscut,  and  found 
a  comparatively  barren  quartz-vein,  carrying  small  spots  of  rich 
ore.  The  enclosing  rock  was  diorite,  and  the  quartz  itself  was 
encased  on  both  sides  by  bands  of  clay  fully  2  feet  thick. 

*  Information  which  I  owe  to  the  courtesy  of  Mr.  S.  H.  Williams,  the  manager. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  39 

On  comparing  the  veins  and  their  encasing  rock,  as  seen  in 
the  workings  of  the  two  mines  on  opposite  sides  of  the  allu- 
vial deposit,  it  is  not  found  necessary  to  go  further  for  the 
origin  of  the  latter.  The  cement  is  underlain  by  a  clay  which 
is  essentially  steatite,  and  is  as  readily  traceable  to  the  neigh- 
boring diorite  as  the  kaolin  at  Kintore  was  deducible  from  the 
granite.  The  green  color  of  the  cement  is  imparted  by 
chlorite,  derived  from  the  decomposition  of  the  epidote  in  the 
diorite.  The  "  ironstone  "  of  the  detritus  overlying  the  gold- 
bearing  part  of  the  deposit  consists  of  fragments  of  altered 
diorite.  The  quartz  in  the  cement  and  the  gold  accompanying 
it  are  both  identical  with  those  of  the  reefs  close  by. 

Here  also  the  topography  confirms  the  suggested  explana- 
tion. The  cement  lies  in  a  shallow  depression,  at  the  upper 
rim  of  which  the  quartz  reefs  cross  the  country.  Further- 
more, these  reefs  traverse  a  low  divide,  which  in  a  rough  way 
separates  the  deposit  from  another,  which  slopes  in  the  oppo- 
site direction.  The  latter  is  known  as  the  Fitzroy  cement.  In 
this  deposit  rich  discoveries  were  made  during  October,  1897. 
A  typical  section  is  exhibited  in  Fig.  21. 

Apart  from  their  importance  as  depositories  of  gold,  the 
cements  have  played  an  interesting  part  in  the  development  of 
the  gold-fields,  because  they  often  cover  the  tops  of  reefs.  In 
Fig.  22  such  an  occurrence*  is  illustrated.  A  similar  feature 
proved  a  serious  hindrance  to  the  recognition  of  the  lodes  at 
Kalgoorlie,  where  worthless  quartz  veins  were  worked  for  some 
time  before  a  trench  traversing  the  cap  of  cement  accidentally 
uncovered  the  top  of  one  of  the  rich  deposits  of  telluride 
ore,  which  did  not  outcrop,  on  account  of  the  comparative 
softness  of  the  lode. 

V. — THEORIES  OF  ORIGIN. 

Of  course,  several  theories  have  been  mooted,  the  most  fan- 
ciful of  which  have  naturally  been  those  of  the  working  miner 
himself.  The  fact  that  the  gold-bearing  cement  is  in  places 
overlain  by  a  considerable  thickness  of  partially-consolidated 
rock  has  led  to  the  supposition  that  the  deposit  was  a  "  deep 
lead;"  while  the  resemblance  to  a  conglomerate  has  caused 
more  than  one  Africander  to  liken  it  to  the  "  banket "  of  the 
Transvaal. 

*  It  is  the  top  of  the  Lady  Shenton  reef,  at  Menzies. 


40  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

The  latter  is  an  immense  shore-deposit  of  gold-bearing 
conglomerates,  now  covered  by  a  series  of  later  sediments. 
Its  dimensions,  comparative  homogeneity  and  persistence  are 
in  striking  contrast  to  the  narrow,  restricted,  irregular  patches 
of  detritus  which  have  been  described  as  occurring  in  West 
Australia.  This  total  unlikeness  renders  unnecessary  any  dis- 
cussion of  a  fancied  similarity  of  origin. 

But  because  this  alluvium  disappears  under  an  overburden 
of  rock,*  the  Australian  digger  easily  fancies  he  is  working  a 
deposit  similar  to  the  "  deep  leads "  with  which  he  became 
familiar  at  Ballarat,  for  example.  A  distinguished  government 
geologist  from  a  neighboring  colony  visited  Kanowna  in  Octo- 
ber, 1897,  and  gave  authority  to  the  term  "  deep  lead "  by 
using  it  himself.  "  Deep  "  it  may  be,  for  that  is  a  comparative 
adjective,  but  a  "  deep  lead "  in  the  technical  sense  it  most 
assuredly  is  not.  On  the  Forest  Hill  divide, f  in  Placer  county, 
California,  and  at  Ores  wick,  in  the  Ballarat  district,  Victoria, 
the  typical  "deep  leads"  occur.  They  are,  as  is  well  known, 
old  (Miocene)  gold-bearing  river  channels,  which  have  been 
saved  from  erosion  by  a  cap  of  lava.  The  lava  probably  over- 
flowed the  original  surface  as  a  steaming  mud,  and  is  now 
found  consolidated  into  a  volcanic  rock  sufficiently  hard  to  need 
little  timbering  when  penetrated  by  underground  workings. 
The  cement  deposits  of  West  Australia  occur  under  an  over- 
burden of  "made  ground;"  that  is  to  say,  both  the  deposit 
itself  and  all  the  material  under  which  it  dips  are  of  distinctly 
detrital  origin,  the  products  of  weathering  and  erosion  accu- 
mulated in  shallow  depressions  of  the  much-decomposed  sur- 
face of  granite  or  diorite. 

It  is  the  placer  of  a  country  destitute  of  running  water. 
The  climatic  conditions  and  the  physiography  of  the  Cool- 
gardie  gold-fields  have  been  carefully  described,  in  order  to 
make  it  evident  why  these  deposits  differ  from  those  of  more 
favored  countries,  like  California  or  New  Zealand.  Surely  it 
is  not  in  keeping  with  the  scientific  method  to  seek  for  fantastic 
or  far-fetched  explanations,  when  processes  in  operation  to-day 

*  Using  the  word  in  its  geological  sense.  Mud  is  "rock"  as  much  as 
granite. 

f  I  append  a  drawing  (Fig.  23)  of  a  typical  deep-lead  recently  examined  by  me 
in  this  particular  locality. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  41 

are  able  to  supply  an  adequate  understanding  of  the  observed 
facts. 

The  quartz  of  the  cement  is  subangular ;  it  has  evidently  un- 
dergone very  little  attrition,  and  suggests,  therefore,  that  it  has 
not  traveled  far.  On  comparing  it  with  the  matrix  of  neigh- 
boring veins,  an  identity  appears  obvious.  The  examination  of 
the  topography  renders  highly  probable  the  derivation  of  the 
one  from  the  other.  The  cementing  material  is  similarly 
found  to  be  the  clay  resulting  from  the  decomposition  of 
the  rock  encasing  the  quartz-veins,  and  varying  according  to 
the  composition  of  that  rock,  whether  it  be  granite  or  diorite. 
Finally,  the  gold  particles  which  have  rendered  the  cement 
worth  mining  are  found  to  be  identical  in  fineness  and  physi- 
cal appearance  with  the  gold  of  the  neighboring  veins,  and  their 
scarcely-rounded  edges  invite  the  conclusion  that  the  gold 
ako  has  not  been  borne  far  from  the  place  of  its  origin.  The 
comparatively  unclassified  condition  of  the  deposits  is  in  keep- 
ing with  the  evidence*  afforded  by  the  material  of  which  they 
are  composed.  The  absence  of  running  water  on  this  desert 
plateau  has  prevented  any  such  sifting-process  as  in  other  re- 
gions leads  to  the  deposition  of  well-defined  layers  of  clay, 
gravel  and  gold  upon  a  clean  bed-rock.  It  is  an  exceptional 
illustration  of  the  working  of  those  agencies  to  whose  un- 
ceasing play  is  due  the  configuration  of  the  earth's  surface ;  it 
is  geological  action  in  its  most  instructive  form. 

VI. — WATER-SUPPLY. 

The  early  history  of  the  gold-fields  of  West  Australia  is  the 
record  of  a  struggle  to  exist  amid  conditions  which  were  inimi- 
cal to  human  life  on  account  of  the  scarcity  of  water.  That 
great  necessity  has  been,  in  some  sort,xsatisfied  by  the  energetic 
action  of  the  government,  supplemented  by  private  enterprise. 
The  gold-fields  are  now  dotted  over  with  condensing-plants, 
which  turn  the  brine  of  the  wells  into  water  fitted  for  the  use 
of  man  and  beast.  Existence  is  thus  rendered  endurable ;  but 
the  mining  industry  is  still  handicapped  by  an  item  of  cost  un- 
known in  more  favored  regions. 

The  water  of  the  country  is  salt,  sometimes  almost  to  the 
point  of  saturation.  Sea-water  contains  3J  per  cent,  of  salts, 
three-quarters  of  this  percentage  being  common  salt,  the 


42  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

chloride  of  sodium.  At  Menzies,  in  September,  1897,  I  found 
one*  of  the  two  important  mines  of  that  district  using  water 
which  contained  17  per  cent,  of  salts,  and  the  manager  in- 
formed me  that  in  December  evaporation  increased  the  amount 
to  30  per  cent.f  For  this  liquid  he  paid  25  shillings  per  thousand 
gallons.  It  came  from  a  neighboring  "soak."  The  condensed 
(distilled)  water,  bought  for  use  in  the  boilers,  cost  £1  per 
hundred  gallons.  Milling  in  a  ten-stamp-mill  was  carried  on 
at  an  average  cost  of  30  shillings  or  $6  per  ton,  the  item  of 
water  alone  amounting  to  13  shillings  or  $3.25  per  ton. 

Under  these  conditions  a  wet  mine  becomes  a  source  of 
revenue.  Many  properties  at  Kalgoorlie,  unable  to  find  pay- 
ore,  lessened  the  expenses  of  development  by  selling  their  water 
to  those  that  had  mills.  The  price  varied  according  to  the  sea- 
son. At  the  Great  Boulder  Main  Reef  mine,  for  example,  the 
lowest  price  paid  for  water  during  1897  was  £3. 10s.  per  thou- 
sand gallons,  and  the  highest  £11. 5s.  This  was  piped  from 
neighboring  shafts,  and  had  not  passed  through  the  condenser ; 
it  therefore  had  the  character  of  sea-water,  but  it  was  four  times 
as  saline. 

An  analysis  of  the  water  of  the  Great  Boulder  Proprietary 
mine  gave  the  following  results.  The  sample  was  turbid,  and 
it  was  found  that  the  matter  in  suspension  amounted  to  5.25 
grains  per  gallon,  or  .075  gramme  per  liter.  The  clear  water 
on  analysis  yielded : 

Grammes  per  liter. 

Silica  (SiO2), .        .  0.038 

Alumina  and  ferric  oxide  (A12O3  and  Fe2O3),        .         .  0.024 

Lime  (CaO), 1.878 

Magnesia  (MgO), ^    ,..._, ;.',.      ,.  8.106 

Soda  (Na2O), 48.470 

Carbonic  anhydride  (CO2), 0.064 

Sulphuric  anhydride  (SO3), 6.026 

Chlorine  (Cl), 67.280 

131.836 
Deduct  oxygen  equivalent  to  chlorine,        .        ,        .     15.150 

116.686 
Combined  water,  organic  matter  and  loss>  .         .        .      8.534 

Total  solids,      .        .      " 125.220 

*  The  Queensland  Menzies  mine. 

f  The  water  of  the  Dead  Sea  varies  from  20  to  26  per  cent,  salts,  and  of  this,  10 
per  cent  is  common  salt. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  43 

The  chief  salts  probably  present  were,  therefore  : 

Grammes  per  liter. 

Calcium  carbonate,  CaCO3, 0. 145 

Calcium  sulphate,  CaSO4, 4.3(55 

Magnesium  sulphate,  MgSO4, 5.189 

Magnesium  chloride,  MgCl2, 15.144 

Sodium  chloride,  NaCl,          . 91.467 

Expressed  in  grains  per  gallon,  the  results  appear  more  strik- 
ing. The  proportion  of  common  salt  amounts  to  no  less  than 
6402.7  grains  per  gallon.  Ordinary  drinking-water  contains 
about  3  grains  of  common  salt  per  gallon. 

The  water-supply  of  the  region  comes  from  two  sources, 
namely,  that  which  has  collected  amid  the  purely  superficial 
deposits  of  debris  and  drift  covering  the  actual  rock-surface, 
and,  secondly,  that  which  has  penetrated  through  the  decom- 
posed rock  down  to  the  zone  where  oxidation  ceases. 

Wherever  a  depression  occurs,  the  prevailing  rocks,  granite 
and  diorite,  are  overlaid  with  a  variable  thickness  of  their 
own  detritus,  which  allows  the  collection  of  rain-water 
and  affords  protection  from  too  rapid  evaporation.  These  are 
known  as  "  soaks."  The  government  geologist  defines  them 
as  "  valleys  silted  up  with  a  thin  covering  of  recent  superficial 
deposits  more  or  less  saturated  with  water."*  At  Hampton 
Plains,  8  miles  from  Coolgardie,  a  supply  of  condensing-water 
has  been  obtained  from  beds  of  this  nature.  The  sectionf  was 
as  follows  : 

Thickness.  Depth. 

Feet.  Feet. 

Clay,  with  ironstone  gravel,                                   .-  27  27 

Fine  sand, 30  57 

Coarse  yellow  sand, 43  100 

Clay,    '                         4  104 

Land  wash,  .         .         .        .      '  „        .         .        .11  115 

Kaolin, 8  123 

Bed-rock,     .        .        .        .        .        .        .        .    39  162 

Water  was  struck  in  the  third  stratum,  described  as  coarse 
yellow  sand.  The  bed-rock  was  granite. 

During  the  wet  season,  some  of  the  depressions  filled  with 
such  accumulations  of  detritus  will  receive  more  water  than 

*  Report  in  connection  with  the  water-supply  of  the  gold-fields.  1897.  A. 
Gibb  Maitland. 

f  From  the  report  just  referred  to. 


44  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

they  can  hold,  and  then  the  eye  becomes  gladdened  for  a  few 
days  by  the  sight  of  water  running  over  the  surface.  As  it 
becomes  diminished  by  evaporation  it  disappears  from  view, 
but  will  be  found  to  linger  in  the  rock-holes,  where  the  supply 
is  maintained  by  the  slow  drainage  of  the  surrounding  porous 
area.  These  are  called  by  the  aborigines  "  guamma "  holes. 
The  life  of  such  natural  wells  depends,  of  course,  on  the  dimen- 
sions of  the  water-bearing  depression  and  upon. the  relative 
porosity  of  the  deposit  which  it  drains. 

These  supplies  are  in  their  nature  uncertain.  The  next  and 
more  important  source  of  supply  is  found  at  the  ordinary 
drainage-level  of  the  country,  namely,  the  horizon  where  the 
oxidation  of  the  surface  ceases  and  the  relatively  hard  unoxi- 
dized  rock  offers  a  partial  barrier  to  the  free  descent  of  the 
waters  which  have  percolated  through  the  overlying  formation. 
The  depth  of  this  zone  will  depend  upon  the  permeability  of 
the  superficial  rock-formation ;  it  varies  from  40  feet  at  Earl- 
ston  to  202  feet  at  Kalgoorlie.  A  characteristic  section  is  that 
given  by  the  well  put  down  on  Reserve  3096,  Coolgardie, 
where  the  Gold-fields  Water  Supply  Department  sunk  165  feet 
and  found  7  feet  of  sand,  47  feet  of  conglomerate  and  111  feet 
of  decomposed  granite.  The  water  was  found  at  the  base  of 
the  last,  just  above  the  unaltered  granite. 

Condensers. — Frequent  mention  has  been  made  of  the  con- 
denser. This  is  a  characteristic  feature  of  every  mining  settle- 
ment in  the  interior  of  Western  Australia,  and  occupies  the 
position  accorded  to  the  public  well  of  a  European  village. 
Without  this  process  of  distillation,  which  renders  the  brack- 
ish water  of  the  wilderness  fit  for  human  consumption,  the 
mining  industry  could  never  have  progressed  beyond  the 
merest  prospecting. 

The  introduction  of  condensers  is  traceable  to  the  sailors 
who  took  a  prominent  part  in  the  early  exploring  expeditions. 
The  name  itself  suggests  this ;  for  a  landsman  would  be  likely 
to  call  the  condenser  a  "  still."  When  the  rush  to  the  new 
gold-fields  occurred,  the  government,  by  erecting  condensers  at 
intervals  along  the  main  lines  of  travel,  did  much  to  diminish 
the  loss  of  life  otherwise  inevitable  in  times  of  wild  excite- 
ment by  reason  of  the  recklessness  of  those  who  joined  the 
stampede  without  due  care  for  the  great  necessity  of  life  in  a 
tropical  desert. 


THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA.  45 

The  process  of  converting  brine  into  drinkable  water  is 
simple.  The  salt  water  is  put  into  a  boiler  and  converted  into 
steam,  which  is  then  condensed  in  vessels  presenting  a  maxi- 
mum of  cooling-surface.  Ship-tanks,  having  a  capacity  of 
400  gallons,  are  commonly  employed  as  boilers,  and  the  con- 
densing apparatus  is  constructed  out  of  the  corrugated  iron 
which  is  everywhere  employed  for  roofing-purposes.  The 
tanks  used  as  boilers  are  usually  set  on  edge  in  pairs,  as  shown 
in  Figs.  24  and  25.  The  average  product  of  each  400-gallon 
tank  is  about  300  gallons  of  distilled  water  daily.  Two  ver- 
tical short  iron  pipes  draw  off  the  steam,  which  passes  into 
condensing  chambers  or  "  coolers."  The  latter  were  originally 
plain  circular  tanks,  which  were  increased  in  capacity  by  the 
addition  of  sections,  increasing  the  height.  Sheets  of  corru- 
gated iron  were  bent  round  until  the  ends  met,  and  these  were 
united  by  riveting  and  soldering.  Several  such  sections  were 
united,  and  a  tubular  tower,  about  30  feet  high  and  3  feet  in 
diameter,  was  the  result.  The  top  and  bottom  were  closed  by 
a  flat  sheet  of  iron.  A  6-inch  pipe  connected  the  towers,  and 
steam  traveled  up  the  one  tower  and  down  the  next. 

This  type  has  been  superseded  of  late  by  annular  chambers. 
An  outer  corrugated  iron  cylinder,  2.5  feet  in  diameter,  sur- 
rounds an  inner  1.5  ft.  cylinder,  so  as  to  leave  an  annular 
space,  6  inches  wide,  which  becomes  the  condensing-chamber. 
No  attempt  is  made  to  supplement  the  cooling  effect  of  the 
surrounding  air,  though  a  brush  shelter  is  sometimes  erected 
so  as  to  ward  oft'  the  direct  rays  of  the  sun.* 

The  daily  expenditure  includes  the  labor  of  two  men,  one  on 
each  shift,  and  the  cost  of  the  fuel  consumed.  A  typical  con- 
denser is  that  erected  on  the  Lake  View  and  Boulder  Junction 
mine,  shown  in  Fig.  4.  This  plant  has  a  capacity  of  1,500 
gallons  of  condensed  water  per  day  and  cost  £100.  The  water 
treated  comes  from  the  mine  and  shaft  and  has  a  specific 
gravity  of  1.03385,  the  total  solids  amounting,  according  to 
the  analyses  of  Mr.  E.  S.  Simpson,  to  4.9308  per  cent,  and  the 
chlorine  to  2.3933  per  cent.  The  cost  averages,  during  the 
cool  season,  5  shillings,  and  during  the  summer  6.5  shillings 


*  For  many  of  these  details  I  am  indebted  to  Mr.  Frank  G.  Grace,  Kalgoorlie, 
and  to  Mr.  Edward  S.  Simpson,  Government  Assayer,  Perth. 


46  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA, 

FIG.  24. 


in  Feed  Water 

"V    \  /      ,' 


o 


Jb 


O 


Plan  of  Ordinary  Condenser. 


FIG.  25. 


FRONT  REMOVED  |  FRONT 

Section  and  Elevation  of  Ordinary  Condenser. 


THE    ALLUVIAL    DEPOSITS    OF   WESTERN    AUSTRALIA.  47 

per  'hundred  gallons  of  condensed  water.  The  condensed 
water  is  sold  at  from  10  to  12  shillings  per  hundred  gallons. 
A  first-class  condenser  would  consist  of  at  least  8  boilers,  each 
having  400  gallons  capacity  and  a  daily  output  of  300  gallons,  of 
condensed  water,  giving  the  plant  a  daily  yield  of  2,400  gallons. 
The  salt  water  is  usually  bought  for  from  2  to  4  shillings  per 
thousand  gallons.  Fuel  costs  20  shillings  per  cord,  and  is  con- 
sumed at  the  rate  of  1  cord  per  thousand  gallons  of  condensed 
water.  Thus  the  cost  would  be  : 

2  men  at  £4  per  week  of  6  days, 27  shillings 

2J  cords  of  wood, 50 .        " 

3, 200  gallons  of  salt  water, 10        " 

Total,    . .        .87  shillings 

This  would  be  at  the  rate  of  36  shillings  per  thousand  gallons. 
During  November,  1897,  condensed  water  sold  for  100  to  150 
shillings  per  thousand  gallons. 

Concerning  the  use  of  salt  water  in  the  stamp-mills  and 
leaching  works  of  Western  Australia,  I  would  say  that  its 
density  is  an  obstacle  to  amalgamation  because  of  the  facility 
with  which  slimes  are  created.  The  finer  particles  of  gold  are 
thus  prevented  from  settling  on  the  copper  plates  of  the  tables, 
and  are  carried  away  in  the  tailings.  At  Kalgoorlie  the  cyanide 
works  use  the  natural  brine  successfully ;  its  magnesia  being 
precipitated  by  lime,  so  as  to  prevent  the  decomposition  of  the 
stock-solution. 

In  order  to  aid  the  development  of  the  mining  industry, 
which  is  still  severely  handicapped  by  the  want  of  a  sufficient 
supply  of  water,  the  government  of  West  Australia  has  decided 
to  carry  out  a  hydraulic  enterprise  of  great  magnitude.  It  is 
proposed  to  supply  5,000,000  gallons  of  fresh  water  per  day  to 
the  Coolgardie  gold-field  by  building  a  pipe-line  from  the  Dar- 
ling range,  where  the  Helena  river  will  be  impounded  by  a 
concrete  dam  100  feet  in  height  and  650  feet  long.  The  source 
of  supply  is  320  feet  above  sea-level,  while  the  service-reser- 
voir at  Coolgardie  will  be  on  Mt.  Burgess,  at  a  height  of  1670 
feet,  or  1350  feet  higher.  These  two  reservoirs  will  be  con- 
nected by  330  miles  of  30-inch  steel-pipe.  Nine  pumping- 
stations  will  be  required.  The  appropriation  for  this  work  is 
$12,500,000.  The  annual  operating  expenses  will  probably 


48  THE    ALLUVIAL    DEPOSITS    OF    WESTERN    AUSTRALIA. 

approximate  $1,600,000,  and  water  will  be  delivered  through  a 
hundred  miles  of  distributing  pipes  at  a  cost  of  3  shillings  and 
6  pence,  or  84  cents,  per  thousand  gallons. 

It  will  occur  to  the  reader  to  ask  whether  boring  for  artesian 
wells  has  been  attempted.  Yes;  in  obedience  to  the  public 
demand,  the  government  put  down  a  bore  at  Coolgardie  which 
reached  a  depth  exceeding  2000  feet  and  found — granite.  The 
geological  conditions  render  an  artesian  flow  of  water  highly 
improbable.  Nevertheless,  in  this  colony,  as  elsewhere  among 
the  arid  tracts  of  Australia,  there  is  a  whispered  hope  of  find- 
ing a  subterranean  river.  As  the  Carson  and  the  Humboldt 
are  swallowed  up  by  the  alkali  wastes  of  Nevada,  so  in  the 
desert  plains  of  this  southern  continent  there  are  many  streams 
w^hich  flow  into  the  interior  and  lose  themselves  in  the  sand 
or  find  for  themselves  an  undergound  channel.*  This  fact  has 
given  rise  to  conceptions,  more  poetic  than  scientific,  of  a  great 
subterranean  river  yet  to  be  discovered,  and  destined  in  days 
to  come  to  make  the  desert  break  forth  into  fertility.  It  is  a 
dream.  No  irrigation  can  turn  the  wastes  of  quartz-sand  into 
waving  fields  of  wheat.  Time,  geological  time,  covering  a 
period  to  measure  which  the  duration  of  a  man's  life  is  an  in- 
adequate unit,  can  alone  render  the  wilderness  fit  for  human 
habitation. 

*  This  occurs  in  Queensland,  where  the  geological  conditions  are  quite  differ- 
ent. Several  very  successful  bore-holes  have  been  put  down,  an  abundant  arte- 
sian flow  being  obtained  at  depths  of  2000  feet  and  over. 


SUBJECT   TO   REVISION. 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


The  Formation  of  Bonanzas  in  the  Upper  Portions  of 
Gold- Veins. 

BY  T.    A.    RICKARD,    DENVER,    COLORADO. 

(Richmond  Meeting,  February,  1901.). 

INTRODUCTORY. 

THE  presentation  to  the  Institute,  eight  years  ago,  of  the  paper 
of  Posepny  on  "  The  Genesis  of  Ore-Deposits  "  has  borne  fruit 
in  much  fresh  investigation,  as  is  evidenced,  for  example,  by 
the  group  of  very  valuable  papers,  by  distinguished  members 
of  the  United  States  Geological  Survey,  read  at  the  Washing- 
ton meeting — discussions  of  general  principles  particularly  sug- 
gestive to  those  who  are  engaged  in  mining. 

Posepny,  in  the  discussion  of  his  famous  treatise,  said  that 
the  present  writer  seemed  to  look  at  every  new  conception  in 
ore-deposition  "  from  the  sole  standpoint  of  its  immediate  use- 
fulness in  mining."*  Protesting  mildly  against  "  sole "  and 
"  immediate,"  I  accept  the  impeachment.  It  calls  for  no  defence. 

THE  DEVELOPMENT  OF  RECENT  THEORIES. 

Given  the  idea  of  an  underground  water-circulation  as  the 
chief  factor  in  the  deposition  of  ore,  the  next  step  in  the  in- 
quiry as  to  the  genesis  of  such  deposits  is  the  endeavor  to  de- 
termine which  particular  part  of  the  general  water-circulation 
is  responsible  for  the  results.  Around  this  question  have  cen- 
tered the  controversies  of  a  generation,  and  to  these  controver- 
sies we  owe  the  gradual  clarification  of  our  ideas  upon  the  pro- 
cesses of  ore-formation.  It  is  unnecessary  to  sketch  here  their 
progress  from  Werner  to  Le  Conte,  who  combated  in  1883  the 
extreme  views  of  the  lateral-secretionists,  and  in  1893  opposed 
the  narrow  interpretation  of  the  ascensionist-theory.  The  gen- 
erally accepted  opinions  of  to-day  are  a  well-deserved  tribute  to 
his  philosophic  discrimination. 

*  Trans.,  vol.  xxiv.,  996. 


2  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

Thanks  to  Prof.  Van  Hise  and  Mr.  Slichter,  whose  work  he 
utilizes,  we  have  now  arrived  at  a  comprehensive  conception 
of  the  underground  circulation,  which  emphasizes  the  conclu- 
sion that  sulphide-ores  are  generally  deposited  by  ascending 
waters.  In  estimating  the  importance  of  this  conclusion,  it  is 
to  be  remembered  that,  apart  from  placers  and  iron-mines,  the 
largest  portion,  by  far,  of  the  ores  exploited  by  the  miner  are 
sulphides.  Morever,  it  has  been  shown  that  the  other,  equally 
essential,  parts  of  the  circulation,  namely,  its  lateral  and  de- 
scending portions,  particularly  the  latter,  also  play  their  part, 
to  which  many  "  secondary  enrichments  "  are  due. 

This  approach  toward  an  understanding  of  the  processes  of 
secondary  enrichment  in  ore-deposits  is  an  extremely  important 
advance  in  the  application  of  geology  to  the  exploitation  of 
mines.  For  such  enrichments  pre-eminently  constitute  the  ore- 
masses  valuable  to  man.  Chemistry  and  physics  may  unite  in 
determining  the  conditions  favorable  to  the  precipitation  of  gold; 
geology  may  unravel  the  intricacies  of  rock-structure,  but  it 
does  not  come  within  the  province  of  these  sciences  to  decide 
whether  a  gold-vein  will  prove  rich  enough  for  profitable  min- 
ing. Mature  knows  no  ratio  of  sixteen  to  one,  or  any  other 
standard  of  monetary  value.  Therefore,  the  determination  of 
the  particular  conditions  favorable  to  the  mere  occurrence  of 
gold-ores  remains  but  a  barren  discovery  until  it  includes  some 
suggestion  as  to  the  search  for  the  richest  portions.  To  the 
geologist,  material  carrying  2  dwts.  of  gold  per  ton  is  as  truly 
an  auriferous  deposit  as  if  it  contained  12  dwts.  per  ton  ;  but, 
under  existing  economic  conditions,  the  miner  may  regard  the 
former  as  only  fit  for  macadam,  and  the  latter  as  potential  of 
fortune. 

When  the  science  of  ore-deposits,  therefore,  has  predicted 
with  certainty  the  places  where  gold  can  be  found,  it  has  ful- 
filled a  conclusive  test  of  a  true  theory.  But  this  means  to  the 
miner  no  more  than  the  restriction  of  his  search  for  profitable 
gold-deposits  to  those  places  where  there  is  any  gold  at  all — a 
restriction  which,  after  all,  amounts  to  little,  for  the  progress 
of  scientific  inquiry  and  practical  exploration  has  rather  en- 
larged than  diminished  the  field  of  the  distribution  of  this 
metal.  A  greater  service  will  be  the  determination  of  the  con- 
ditions which  control  the  formation  and  distribution  of  those 


THE    FORMATION    OF    BONANZAS    IN  GOLD-VEINS.  6 

particular  portions  of  the  multitudinous  deposits  of  gold  which 
constitute  the  secondary  enrichments  of  the  geologist  and  the 
bonanzas  of  the  miner. 

'Such  a  desired  consummation  seems  now  to  be  nearer  of 
attainment.  The  practical  result  of  the  papers  of  Messrs. 
Van  Hise,  Emmons  and  Weed  will  be  to  direct  attention  to  the 
one  line  of  inquiry  most  useful  to  the  miner.  Unquestionably 
the  theories  of  secondary  enrichment  have  been  largely  sug- 
gested by  the  experience  of  the  men  whom  the  geologists  have 
met  at  the  mines ;  and  the  invaluable  assistance  thus  given  to 
mining  engineers  is  a  pleasant  outcome  of  such  an  exchange 
of  views. 

THE  ENRICHMENT  OF  GOLD- VEINS  ^"EAR  THE  SURFACE. 

A  quartz  lode  carrying  gold  in  association  with  pyrite  is  here 
taken  as  the  type  of  deposit  under  discussion.  In  lodes  of  this 
kind,  it  is  a  common  experience  to  find  bodies  of  rich  oxidized 
ores  extending  to  a  variable  depth  from  the  surface.  In  this 
general  phenomenon  of  enrichment  two  processes  must  be 
separately  recognized,  namely,  relative  enrichment  by  a  method 
of  natural  concentration  and  positive  enrichment  by  the  de- 
position of  additional  gold  through  secondary  reactions. 

Enrichment  by  Concentration. 

The  iron  sulphide  accompanying  the  gold  is  removed  by 
weathering.  Weathering  is  a  process  of  chemical  decomposi- 
tion and  mechanical  disintegration  in  which  oxidation  is  aided 
by  the  shattering  of  the  rock  due  to  the  alternate  expansion 
and  contraction  of  the  water  present  in  its  pores,  seams  and 
cavities.  The  depth  to  which  these  effects  extend  will  depend 
upon  the  facilities  afforded  for  the  penetration  of  surface- 
waters  carrying  free  oxygen;  and  it  will  be  regulated  by  the 
local  groundwater-level.  The  results  observed  usually  cease  at 
the  groundwater-level  because, at  that  horizon  the  descending 
surface-waters  become  mingled  with  the  larger  body  of  neu- 
tralized water,  and  so  lose  their  free  oxygen.  When,  however, 
they  can  find  channels  permitting  a  relatively  rapid  passage, 
they  may  not  become  at  once  diffused,  and  may  thus  continue 
their  oxidizing  action  even  below  that  level.  But  the  actual 
lowering  of  the  groundwater-level,  by  a  change  of  surface  alti- 


4  THE    FORMATION    OF    BONANZAS    IN    GOLD-VEINS. 

tude  or  hydrostatic  conditions,  affords  the  chief  factor  in  en- 
larging the  scope  of  such  oxidizing  action  on  the  part  of  the 
surface-waters. 

The  chemistry  of  the  process  is  pretty  well  understood,  and 
need  not  be  discussed  here. 

In  the  case  of  enrichment  by  concentration,  the  evidence 
indicates  that  the  leaching  and  removal  of  the  pyrite  has  been 
affected  without  shifting  the  gold,  which  remains  behind  in  its 
native  state.  I  have  specimens  from  Idaho  and  West  Australia 
exhibiting  crumbly  native  sulphur,  within  the  cubic  cavities 
vacated  by  the  pyrite,  and  in  those  from  West  Australia  there 
is  also  gold  in  fine  crystals  which  are  readily  shaken  loose. 
The  removal  of  pyrite  ;  the  occurrence  of  fine  particles  of  gold 
in  the  vacant  casts  produced  by  this  removal,  and  the  forma- 
tion of  a  sintery  honeycombed  mass  of  iron-stained  quartz  are 
familiar  aspects  of  the  process  of  natural  concentration. 

Weathering,  then,  by  removing  the  baser  and  more  soluble 
constituents  of  the  vein,  decreases  the  weight  without  dimin- 
ishing the  volume  of  the  ore,  which  thus  becomes  so  much  the 
richer  per  ton.  Iron-stained  gossan,  rich  in  gold,  is  a  familiar 
occurrence  in  mining,  and  the  frequent  development  of  such 
material  has  had  a  far-reaching  effect  in  determining  the  char- 
acter of  the  industry.  Apart  from  the  richness  of  such  oxi- 
dized ore,  its  metallurgical  docility  greatly  enhances  its  value. 
In  comparison  with  the  unaltered  and  relatively  refractory 
pyritic  ores,  the  oxidized  material  is  not  only  easier  to  crush, 
but  also  easier  to  treat  by  amalgamation,  chlorination,  etc. 
Hence  the  contrast  which  is  occasionally  offered  between  the 
early  successes  of  the  discoverers  of  a  gold-vein  and  the  sub- 
sequent troubles  of  the  mining  company  which  buys  their 
property.  The  gossan  of  the  gold-vein  has  been  the  source  of 
a  large  part  of  the  world's  store  of  the  precious  metal ;  and  to 
it  we  owe  the  successful  beginnings  of  many  districts,  which, 
if  they  had  been  compelled  to  commence  operations  upon  re- 
fractory pyritic  ore,  would  have  waited  long  for  their  active 
development. 

Secondary  Enrichments  Due  to  Descending  Surface-  Waters. 

The  diagnosis  of  the  general  process  by  which  these  are 
formed  by  descending  waters  has  been  stated  in  clear  terms 
in  the  contributions  of  Messrs.  Van  Hise,  Emmons  and  Weed. 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS.  5 

The  occurrence  of  restricted  bodies  of  extraordinarily  rich 
gold-bearing  quartz  has  been  a  startling  feature  of  gold-mining 
in  all  countries.  From  them  fortunes  have  been  made  with 
picturesque  suddenness ;  and  by  means  of  them  the  inexperi- 
enced have  been  led  into  sanguine  expectations,  the  failure  of 
which  has  brought  disasters  not  less  romantic,  though  much 
less  welcome  to  their  victims.  Such  instances  have  furnished 
matter  for  proverbs  concerning  the  uncertainty  of  mining ;  but 
they  are  soon  forgotten.  Nevertheless,  the  uncertain  occur- 
rences of  rich  ore  on  which  they  are  based  present  an  important 
feature  of  the  ore-deposits  in  all  gold-mining  districts,  though 
they  are  more  particularly  characteristic  of  desert  regions, 
such  as  the  area  of  the  Great  Basin,  stretching  between  the 
Rocky  Mountains  and  the  Sierra  Nevada,  and  also  those  arid 
parts  of  Australia  and  West  Australia  which  have  yielded  so 
much  of  the  wealth  of  the  colonies. 

The  outcrop  of  a  gold-vein  is  not  always  the  richest  portion. 
The  sintery  gossan  formed  at  the  immediate  surface  may  be 
poor  in  gold,  and  yet  may  be  succeeded  near,  or  even  below, 
the  water-level,  by  extremely  rich  masses  of  half-decomposed 
pyritic  ore.  In  such  cases  it  would  appear  that  the  gold  had 
been  leached  out  of  the  oxidized  portion  of  the  lode,  and  had 
migrated  in  the  wake  of  the  iron  until  precipitated,  so  as  to 
form  the  secondary  enrichment  now  under  discussion. 

In  considering  the  formation  of  these  bonanzas,  one  of  the 
first  problems  presented  is  the  question  of  the  mode  of  occur- 
rence of  the  gold  in  the  pyritic  quartz  of  the  lode.  The  evidence 
as  yet  available  indicates  that  the  gold  does  not  exist  in  chemi- 
cal combination  with  the  iron  sulphide  of  the  pyrite,  but  usually 
occurs  in  minute  filaments  or  crystal  aggregates  distributed 
through  the  substance,  and  especially  along  the  structural 
planes,  of  the  pyrite.  In  my  collection  I  have  a  handful  of 
fragments  of  pyrite  obtained  from  the  Orphan  Boy  mine,  in 
Boulder  county,  Colo.  This  mine  was  the  beginning  and  end 
of  a  mining  excitement  which  happened,  in  the  spring  of  1892, 
in  connection  with  a  locality  named  Copper  Rock.  Under  a 
magnifying-glass  the  specimens  exhibit  little  crystals  of  gold, 
which,  by  the  rounding  of  their  edges,  appear  in  places  as 
globules  distributed  over  the  facets  and  in  the  crevices  of  the 
pyrite. 

The  behavior  of  such  gold-ore  under  metallurgical  treatment 


6  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

also  suggests  strongly  that  its  usual  mode  of  occurrence  is 
analogous  to  the  above  example.  When  gold-bearing  pyrite  is 
treated  by  cyanidation,  the  gold  may  be  leached  out  without 
deformation  of  the  pyrite  or  any  other  change  in  its  appearance 
except  the  acquisition  by  its  facets  of  a  pitted  surface  suggest- 
ing cavities  left  by  the  removal  of  a  soluble  constituent.  More- 
over, there  are  many  mining  districts  yielding  gold  from  pyritic 
veins  in  which  the  native  metal  is  rarely  seen.  The  ores  of 
G-ilpin  county,  in  Colorado,  for  example,  contain  an  average  of 
from  10  to  15  per  cent,  of  iron  and  copper  pyrites ;  and  I  know 
from  frequent  trial  that  when  crushed  and  washed  in  a  pan, 
such  material,  even  though  very  rich,  will  not  yield  a  "  color," 
that  is,  a  speck  of  visible  metallic  gold.  Nevertheless,  in  the 
stamp-mill  these  ores  yield  their  gold  to  amalgamation,  indicat- 
ing by  their  behavior  in  this  respect  that  the  gold  is  in  a  condi- 
tion of  such  freedom  as  to  permit  its  separation  by  a  crude 
mechanical  process,  and  its  subsequent  ready  combination  with 
mercury  so  as  to  form  an  amalgam. 

The  gold  which  occurs  thus  in  the  pyrite  of  the  quartz-vein 
is  soluble  in  many  natural  reagents,  some  of  which  are  formed 
in  the  very  process  of  weathering  which  leaches  the  pyrite, 
while  others  are  known  to  be  present  in  the  surface-waters 
which  circulate  through  the  lode-fractures  under  observation 
at  the  present  day.  By  whatever  means  it  is  dissolved,  the 
gold  is  then  supposed  to  be  carried  by  the  surface-waters* in 
their  descent  toward  the  groundwater-level,  where  it  is  pre- 
cipitated under  conditions  to  be  discussed  in  due  course. 

Solvents. 

In  the  process  of  weathering,  the  pyrite  yields  many  subor- 
dinate compounds,  such  as  sulphuretted  hydrogen,  sulphurous 
and  sulphuric  acid,  and  proto-  and  sesqui-sulphates  of  iron.  Of 
the  latter,  the  sesqui-sulphate,  Fe2(S04)3,  is  a  solvent  for  gold, 
and  has  been  cited  by  Wurtz  and  Le  Conte  in  early  discussions 
concerning  the  origin  of  masses  of  native  gold  in  oxidized 
ores.  Dr.  Richard  Pearce,  in  later  years,  has  frequently  drawn 
attention  to  the  probability  that  this  sesqui-sulphate  is  a  factor 
in  the  process  of  gold-deposition.* 

*  Presidential  Address,  Proc.  Colo.  Sci.  Soc.,  vol.  iii.,  part  ii.  (1889),  p.  244. 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS.  7 

The  gold-deposits  in  the  cavernous  quartzite  of  Battle  Mt., 
Colo.,*  have  characteristics  which  appear  to  confirm  this  view. 
In  these  ores  large  pieces  of  native  gold,  of  a  nuggety  appear- 
ance, but  really  crystalline  in  structure,  have  been  found  asso- 
ciated with  horn-silver  and  the  sesqui-sulphate  of  iron.  The 
latter  occurs  in  lumps,  mixed  with  clay ;  and  although  these 
are  very  rich  irt  gold,  the  gold  occurs  in  a  form  not  to  be  de- 
tected by  careful  panning.  Analyses  of  several  large  lots  of 
ore  showed  the  presence  of  12  per  cent,  of  the  hydrated  sesqui- 
sulphate  of  iron.f 

But  other  solvents,  capable  of  doing  this  work,  also  occur  in 
nature,  and,  although  the  amount  of  any  one  of  them  to  be  de- 
tected in  existing  surface-waters  may  be  minute,  we  have  to  re- 
member that  the  processes  of  nature  are  permitted  so  much 
more  time  than  those  of  the  laboratory  that  the  dilution  of  the 
solution  is  compensated  by  the  quantity  of  it. 

Most  writers  refer  to  chlorine  as  a  possible  reagent.  Such  a 
reference  is  suggested  not  only  because  it  is  a  prominent  re- 
agent in  the  metallurgical  practice  of  to-day,  but  also  by  the 
fact  that  it  has  a  wide  distribution  throughout  nature  in  the 
form  of  common  salt.  This  is  most  apparent  in  arid  regions 
where  evaporation  causes  concentrated  solutions  to  be  formed. 
Thus,  in  the  deserts  of  West  Australia  the  water  encountered 
in  the  mines  is  always  brackish,  and  frequently  contains  more 
salt  than  the  sea.J  The  water  of  the  Great  Boulder  Proprie- 
tary mine,  at  Kalgoorlie,  in  1897,  contained  6402  grains  of 
common  salt  per  gallon.  §  A  considerable  amount  of  magne- 
sium chloride  was  also  present.  In  some  of  the  water  used  in 
the  stamp-mills,  and  obtained  from  temporary  "lakes," ||  the 
salts  were  present  up  to  the  point  of  saturation  and  the  liquid 
carried  further  salts  in  suspension,  so  that  the  amount  reached 
as  high  as  30  per  cent.,  rendering  the  term  "  brine  "  more  suit- 
able than  "  water."  This  liquid  contained  17  per  cent,  of  salts 

*  F.  Guiterman,  "Gold  Deposits  in  the  Quartzite  Formation  of  Battle  Moun- 
tain, Colorado,"  Proc.  Colo.  Sci.  Soc.,  vol.  iii.,  part  iii.  (1890),  pp.  264-268. 

t  Ibid.,  p.  266. 

J  Sea-water  contains  3£  per  cent,  of  salts,  three-quarters  of  which  is  common 
salt,  the  chloride  of  sodium. 

\  This  is  equivalent  to  9  per  cent. 

||  "Sinks"  or  salt-marshes.  They  form  an  important  feature  of  the  physiog- 
raphy of  West  Australia, 


8  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

in  solution  even  when  most  diluted  by  recent  rains,  and  it 
therefore  afforded  a  parallel  to  the  Dead  Sea,  the  waters  of 
which  contain  from  20  to  26  per  cent,  of  salts,  of  which  10  per 
cent,  is  common  salt.  These  excessive  percentages  are  not  due 
to  the  presence  of  deposits  of  salt  in  the  rocks  of  the  district, 
but  simply  to  the  concentration  brought  about  by  the  excessive 
evaporation*  which  takes  place  in  a  hot,  arid  climate. 

Mine-waters  frequently  contain  a  noteworthy  quantity  of 
chlorine,  as  chloride  of  sodium.  At  the  Mammoth  mine,  in 
Final  county,  Arizona,  the  water  carries  five  grains  of  salt  per 
gallon,  while  the  well-water,  used  in  the  stamp-mill,  situated  in 
the  valley  below  the  mine,  contains  twice  as  much.f  This 
would  be  equivalent  to  six  grains  of  free  chlorine  per  gallon. 
The  larger  amount  contained  in  the  water  from  the  well,  as 
compared  with  that  in  the  drainage  of  the  mine,  suggests  the 
results  of  surface-leaching.  Even  in  mountainous  districts, 
such  as  Cripple  Creek,  Colo.,  the  mine-waters  carry  chloride 
of  sodium  to  a  noteworthy  extent.  The  water  of  the  Inde- 
pendence mine  contains  three  grains  per  gallon. 

Another  suggestive  feature  is  offered  by  the  abundance  of 
horn-silver  or  cerargyrite,  the  chloride  of  silver,  throughout  the 
dry  tracts  of  Arizona,  New  Mexico  and  Nevada.  J  Prof.  Pen- 
rose  emphasizes  this  interesting  fact,  and  connects  it  with  the 
bodies  of  salt  water  which  still  survive  in  places  as  "  sinks  " 
and  "  lakes. "§  Furthermore,  the  oxi-chloride  of  copper,  ata- 
camite  (which  derives  its  name  from  the  Atacama  desert,  be- 
tween Chili  and  Peru),  is  frequent  in  these  regions.  Another 
and  more  uncommon  mineral  may  also  be  mentioned  in  this 
connection.  In  the  Mammoth  mine,  already  cited,  and  in  the 
well-known  Vulture  mine,  both  in  Arizona,  the  precious  metals 
are  associated  with  vanadinite,  which  contains  chlorine  as  a 
chloro-vanadate  of  lead,  3Pb3(V04)PbCl4.||  Thus  the  chlorides 

*  The  rate  of  evaporation,  in  the  region  mentioned,  has  been  estimated  to  be 
as  much  as  7  ft.  per  annum. 

f  As  I  am  informed  by  Mr.  T.  G.  Davey. 

I  The  general  occurrence  of  horn-silver  in  the  outcrops  of  lodes  throughout 
the  southern  parts  of  Arizona  and  New  Mexico  has  originated  the  term  "chlorid- 
ing"  which  the  miners  employ  as  a  synonym  for  "prospecting,"  which,  by  the 
way,  the  Australian  calls  "fossicking." 

g  R.  A.  F.  Penrose,  Jr.,  "The  Superficial  Alteration  of  Ore-Deposits,"  The 
Journal  of  Geology,  vol.  ii.,  No.  3,  1894.  II  Dana. 


THE    FORMATION    OF    BONANZAS    IN    GOLD-VEINS.  9 

of  copper,  lead  and  silver  are  found  in  the  oxidized  ores  of 
these  regions,  while  the  corresponding  combination  of  gold  is 
absent.  The  explanation  is  obvious.  The  chloride  of  gold  is 
an  unstable  and  readily  soluble  compound,  while  the  minerals 
formed  by  the  corresponding  combination  with  the  baser 
metals  are  comparatively  insoluble  in  water,  especially  the 
chloride  of  silver,  for  the  abundance  of  which  there  is  therefore 
a  good  reason.  It  remains  but  to  add  that,  in  several  Arizona 
mines  which  I  have  sampled,  the  ores  above  the  water-level 
carried  a  notable  proportion  of  silver  with  very  little  gold, 
while  in  depth  the  silver  contents  have  diminished  and  the 
gold  has  increased,  especially  in  the  vicinity  of  the  water- 
level.* 

Of  the  many  reagents  which  would  liberate  the  chlorine 
from  salt,  it  is  only  necessary  to  mention  ferric  sulphate  and 
sulphuric  acid,  both  derived  from  the  ordinary  oxidation  of 
pyrite.  The  hydrochloric  acid  thus  formed  would  yield  free 
chlorine  in  the  presence  of  manganese  oxides,f  which  are  very 
prevalent  in  the  upper  portion  of  gold-lodes,  in  the  form  of  the 
black  earthy  mineral,  psilomelane. 

There  are  other  possible  solvents  which  need  not  be  dis- 
cussed here. 

Predpitants. 

Whatever  the  solvents  which  leach  out  the  gold  from  the 
superficial  portions  of  the  vein,  there  is  assuredly  no  lack  of 
precipitants.  It  is  probable  that  the  gold  does  not  migrate  far 
before  encountering  conditions  which  compel  deposition.  Even 
when  it  is  eventually  carried  to  a  considerable  distance  it  is 
most  likely  that  such  removal  is  effected  by  alternating  stages 
of  precipitation  and  solution. 

Organic  matter  is  a  probable  precipitant  for  the  gold  in 
such  surface-waters.  It  exists  deeper  than  hasty  observation 
would  suggest.  At  the  Great  Boulder  Main  Reef  mine,  at 
Kalgoorlie,  I  saw  the  roots  of  trees  which,  in  their  energetic 
search  for  moisture,  had  attained  a  depth  of  85  ft.  below  the 
surface ;  and  at  the  Sugar  Loaf  mine,  near  Kunanalling  (also 


*  I  may  instance  two  well-known  mines,  the  Mammoth  and  the  Commonwealth. 
t  See  the  experiments  made  by  Dr.  Don,  to  test  this  matter,  Trans,,  xxvii., 
p.  599. 


10  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

in  West  Australia),  I  saw  a  similar  occurrence  at  a  depth  of 
74  ft* 

Another  agency  which,  under  certain  chemical  conditions, 
is  a  probable  factor  in  reducing  the  gold  from  surface-waters, 
is  pyrite  itself.  Thus,  the  gold  dissolved  from  the  decomposed 
pyrite  at  the  surface  may  be  precipitated  upon  the  unoxidized 
pyrite  deeper  down.  Among  the  exhibits  belonging  to  the 
Colorado  Scientific  Society  is  a  bottle  containing  cubes  of 
pyrite,  on  the  faces  of  which  crystals  of  gold  are  to  be  seen. 
They  are  the  result  of  one  of  Mr.Pearce's  experiments.  The  gold 
of  a  Cripple  Creek  ore  was  dissolved  by  using  common  salt,  sul- 
phuric acid  and  psilomelane  as  reagents,  the  chlorine  being 
thus  obtained  in  a  manner  analogous  to  conditions  which  prob- 
ably occur  in  nature.  This  solution  was  placed  in  a  small 
bottle,  and  to  it  were  added  a  few  large  pure  crystals  of  pyrite 
from  the  St.  Louis  mine,  at  Leadville.  After  several  months 
the  gold  became  precipitated  in  the  manner  described.  In 
this  connection  the  story  of  Daintree's  experiment,  which  I 
have  quoted  before, f  is  worth  repeating.  In  1871,  Daintree 
commenced  a  series  of  experiments  at  Dr.  Percy's  laboratory 
at  the  Royal  School  of  Mines,  London.  In  a  number  of  small 
bottles  he  placed  a  solution  of  chloride  of  gold,  and  to  each  he 
added  a  crystal  of  one  of  the  common  metallic  sulphides,  such 
as  pyrite,  blende,  galena,  etc.  At  the  time  when  Daintree 
died,  a  few  years  later,  no  results  could  be  discerned ;  but  one 
of  the  bottles,  containing  the  gold  solution  and  a  crystal  of 
common  pyrite,  was  removed  to  Dr.  Percy's  private  laboratory, 
in  Gloucester  Crescent,  and  there,  in  1886,  the  experiment  was 
completed  by  the  discovery  of  a  cluster  of  minute  crystals  of 
gold  upon  the  smooth  surface  of  the  pyrite.  The  experiment 
had  occupied  fifteen  years ;  and  on  account  of  its  very  length 
it  may  be  said  to  have  more  nearly  approached  the  actual  con- 
ditions occurring  in  nature. 

In  a  case  like  that  of  the  "  Indicator,"  at  Ballarat,  which  I 


*  Since  writing  the  above  I  have  read  Professor  Vogt's  very  valuable  contribu- 
tion, and  I  note  that  he  mentions  having  seen,  among  the  mineral  exhibits  at 
Paris,  specimens  of  such  roots,  from  the  Great  Boulder  Main  Reef  mine,  on 
which  gold  had  actually  been  precipitated.  "  Problems  in  the  Geology  of  Ore- 
Deposits,"  pamphlet  edition,  page  43. 

f  Trans.,  xxii.,  313. 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS.  11 

have  lately  described  again,*  it  maybe  questioned  whether  it  is 
the  pyrite  in  the  thin  seam  of  graphitic  slate  or  the  carbonaceous 
matter  of  the  latter  which  causes  the  precipitation  of  the  gold. 
Even  if  the  pyrite  was  the  decisive  factor,  it  must  be  remem- 
bered that  it,  in  turn,  probably  owed  its  previous  deposition  to 
the  action  of  the  carbonaceous  precipitant  in  the  Indicator 
seam.  This  would  apply  also  to  the  beds  of  black  slate  which 
have  had  so  marked  an  influence  on  the  occurrence  of  gold  in 
the  Gympie  district, f  Queensland,  but  it  would  not,  I  think, 
be  applicable  to  the  Rico  deposits, J  where  pyrite  is  not  an 
especial  constituent  of  the  black  shales,  as  compared  with  the 
sandstone  beds  of  the  same  stratified  series. 

Solution  and  Precipitation. 

It  is  to  be  noted  that  in  the  two  examples  of  ore-forming  pro- 
cesses which  have  been  considered,  the  gold  in  the  superficial 
part  of  the  vein  is  supposed,  in  one  case,  to  remain  in  the  gos- 
san after  the  pyrite  has  been  removed,  while  in  the  other  in- 
stance the  gold  also  is  dissolved  and  carried  elsewhere.  This 
may  appear  contradictory.  It  is  a  good  illustration  of  the  per- 
plexities arising  from  the  application  of  chemical  hypotheses  to 
the  theory  of  ore-deposition. 

Nature  knows  no  interval  of  inaction ;  solution  is  going  on  at 
one  time,  precipitation  at  another.  The  gold  is  constantly  the 
object  of  one  or  the  other  activity.  After  the  pyrite  is  removed, 
or  while  it  is  still  undergoing  leaching,  the  gold  is  being  dis- 
solved, but  more  slowly  than  the  baser  metals.  That  which 
remains  to  enrich  the  gossan  may  well  be  supposed  to  be  the 
survival  from  a  larger  quantity  of  gold  which  has  been  under- 
going slow  solution.  The  gold  which  was  deposited  deeper 
down,  from  the  surface-waters,  may,  as  erosion  takes  away  the 
upper  part  of  the  vein,  eventually  find  itself  close  to  the  sur- 
face and  undergo  re-solution.  It  is  a  question  whether  the 
mining  of  to-day  breaks  in  upon  the  gold-deposits  at  one  stage 
or  another  of  a  continuous  process.  The  miner  finds  the  bal- 
ance of  gold  left  on  deposit  from  a  current  account  in  Nature's 

*  "The  Indicator  Vein,  Ballarat,  Australia."     Trans.,  xxx.,  1004. 
f  J.  K.  Don.     "The  Genesis  of  Certain  Auriferous  Lodes."     Trans.,  xxvii., 
577-580. 

J  The  Enterprise  Mine,  Eico,  Colorado."     Trans.,  xxvi. ,  906. 


12  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

bank.  Solution  and  precipitation  are  everywhere  in  action ;  it  is 
the  excess  of  one  or  the  other  which  determines  the  formation 
of  ores. 

THE  DISTRIBUTION  OF  ORE-BONANZAS. 

The  shifting  of  the  zone  of  oxidation  is  a  principal  factor  in 
determining  the  distribution  of  rich  ores.  By  the  erosion  of 
the  superficial  portions  of  the  vein,  in  common  with  the  en- 
closing rock,  the  further  downward  penetration  of  the  oxidiz- 
ing agencies  is  facilitated.  The  depression  of  the  ground- 
water-level  lowers  the  zone  at  which  precipitation  of  gold,  from 
descending  surface-waters,  takes  place,  while,  on  the  other  hand, 
when  a  change  in  the  hydrostatic  level  causes  the  groundwater 
to  rise,  the  zone  of  deposition  moves  up.  In  both  cases  the 
tendency  is  to  give  vertical  extension  to  the  rich  mass  of  sec- 
ondary gold-ore,  and  thus  to  produce  the  occurrence  which  the 
miners  term  a  "  shoot." 

Erosion  is  followed  by  another  result,  in  itself  of  great  im- 
portance to  gold-mining.  The  steady  removal  of  the  super- 
ficial part  of  the  vein  causes  the  lower  portion,  which  has  been 
enriched  at  or  below  the  groundwater-level,  to  undergo  a  rela- 
tive elevation  by  being  brought  nearer  to  the  surface.  In  this 
way  the  bonanza-zone,  in  process  of  time,  may  become  the  out- 
crop. This  appears  to  me  to  explain  the  formation  of  the  extra- 
ordinarily rich  bunches  of  specimen-quartz,  such  as  made  West 
Australia  famous  in  1894  and  1895,  and  started  the  mining 
stampedes  of  other  days  elsewhere.  In  many  instances  for- 
tunes have  been  gathered  almost  at  the  grass-roots  from  veins 
which,  on  systematic  development,  have  proved  unprofitable. 
The  gold-quartz  veins  of  West  Australia  traversed  rocks  of 
great  geological  antiquity  which  have  not,  during  late  geolog- 
ical periods,  undergone  any  notable  disturbance.  We  do  not 
know  at  what  period  the  veins  were  formed ;  but,  even  though 
their  formation  dates  no  further  back  than  the  beginning  of 
the  Tertiary,  they  have  since  been  continuously  exposed  to  the 
same  quiet  forces  of  erosion  which  have  leveled  the  region 
until  it  appears  as  an  arid  table-land  strewn  with  the  wreckage 
of  geological  time. 

Whatever  the  alternations  of  slow  depression  and  elevation 
which  have  affected  this  region,  as  part  of  a  continental  area, 
it  is  certain  that  erosion  has  been  long  at  work  with  patient 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS.  13 

constancy.  Throughout  this  period  chemical  agencies  have 
been  active  in  the  zone  of  weathering,  near  the  surface,  remov- 
ing the  gold  to  the  zone  of  precipitation,  near  the  groundwater. 
Whatever  the  slight  changes  which  have  marked  the  level  of 
the  groundwater  from  time  to  time,  erosion  has  continued  un- 
interruptedly, and  therefore  it  has  steadily  gained,  with  the 
result  that  the  enriched  portion  of  the  vein  has  been  brought 
nearer  and  nearer  to  the  actual  surface,  until  it  finally  appears 
as  the  outcrop  which  rewards  the  search  of  the  prospector. 

The  Localization  of  Ore-Shoots. 

To  the  miner  the  localization  of  these  richer  portions  of  the 
vein  is  of  more  immediate  practical  interest  than  the  theory  of 
their  origin.  A  gold-vein  is  not  a  homogeneous  mass  of  aurif- 
erous quartz,  of  tabular  form,  penetrating  the  rocks  like  a 
sheet  of  paper,  but  rather  as  an  irregular  occurrence  of  ore,  the 
composition  and  shape  of  which  are  very  variable,  because  they 
are  the  result  of  chemical  agencies  and  structural  conditions  of 
great  complexity.  While  the  traces  of  the  agencies  which  pre- 
cipitated the  ore  are  obscure,  because  they  have  been  largely 
obliterated  by  subsequent  chemical  action,  the  relation  between 
the  vein  and  its  encasing  rock  can  often  be  traced  by  observa- 
tion. In  this  direction  the  miner  obtains  great  aid  from  the 
geologist.  The  transactions  of  this  Institute  and  the  publica- 
tions of  the  IT.  S.  Geological  Survey  contain  numerous  clear 
expositions  of  such  structural  relations.  The  monographs  on 
the  Leadville  and  Eureka  mining  districts  may  be  especially 
instanced  as  affording  striking  examples  of  the  direct  applica- 
tion of  geology  to  underground  work. 

Australia. — One  of  the  best  examples  of  the  localization  of 
rich  ore  came  under  my  notice  in  1890  in  the  Bright  mining 
district.  Bright  is  geographically  in  the  Australian  Alps,  and 
geologically  in  the  Upper  Silurian  slates  and  sandstones. 
Though  these  rocks  have  undergone  metamorphism,  and  ex- 
hibit a  well-developed  cleavage,  yet  their  bedding  has  not  been 
obliterated.  The  veins  cross  the  bedding-planes  of  the  enclos- 
ing country  both  in  strike  and  dip.  When  investigating  the 
distribution  of  the  ore  in  the  mines  of  this  district,  I  found  that 
the  ore-shoots  had  a  pitch  corresponding  with  the  line  of  inter- 
section between  vein  and  country.  This  was  well  illustrated  at 


14  THE    FORMATION    OF    BONANZAS    IN    GOLD-VEINS. 

the  Shouldn't  Wonder  mine,  7  miles  from  the  town  of  Bright. 
The  lode  was  a  simple  quartz  vein  from  15  to  24  in.  wide, 
carrying  a  small  percentage  of  pyrite.  It  had  a  strike  of  N. 
28°  W.  of  K  and  a  dip  to  the  NE.  of  about  75°,  while  the 
country  dipped  SW.  79°  and  had  a  strike  of  K  55°  W.  The 
plane  of  the  vein  cut  across  the  beds  of  the  country  and  the 
intersections  thus  produced  were  to  be  seen  along  the  foot-wall 
of  the  lode  as  lines,  pitching  42°  to  46°  southward.  While  the 
foot-wall  was  more  regular  than  the  hanging,  and  therefore  ex- 
hibited this  feature  best,  yet  the  hanging  also  carried  lines  cor- 
responding with  those  observed  on  the  opposite  wall. 

The  boundaries  of  the  ore-shoots  in  the  mine  followed  these 
lines ;  and  the  longitudinal  section  of  the  workings,  as  seen  on 
the  mine-maps,  proved  also  that  these  lines  of  intersection  had 
an  inclination  which  coincided  with  the  trend  of  the  ore-bodies, 
as  stoped  out  between  the  four  successive  upper  levels  of  the 
property. 

At  the  Myrtle  mine,  in  the  same  district,  there  was  the  same 
correlation  between  the  pitch  of  the  ore-bodies  and  the  line  of 
intersection  of  the  wall  of  the  lode  with  the  bedding-planes  of 
the  enclosing  country.  The  stratification  was  distinct,  the 
rocks  consisting  of  altered,  silicified  slates  of  a  gray  to  gray- 
blue  tint.  In  the  stopes  above  the  700-ft.  level  the  pay-ore  was 
separated  from  the  normal  valueless  quartz  of  the  lode  by  a 
small  step,  due  to  the  irregular  fracture  of  the  vein  in  crossing 
two  beds  of  unequal  hardness.  It  marked  the  line  of  inter- 
section between  lode-plane  and  country  bedding,  and  also 
proved  to  be  the  boundary  of  the  pay-shoot.  In  the  different 
portions  of  the  mine  the  variation  in  the  dip  of  the  country 
produced  variations  in  the  angle  of  the  lines  of  intersection, 
and  also  in  the  pitch  of  the  ore-shoots. 

It  is  not  often  that  the  formation  traversed  by  a  vein  has 
such  a  simple  structure  as  was  presented  by  these  Silurian 
sedimentary  rocks;  but  it  is  probable  that  in  other  districts 
also  the  pitch  of  the  ore-bodies  may  have  been  determined  by 
structural  conditions  of  a  similar  kind,  which  have  been  ob- 
scured, however,  by  metamorphism. 

Colorado. — Experience  has  shown  that  the  intersection  of 
fractures  favors  the  occurrence  of  rich  ore-bodies.  An  inter- 
esting example  was  afforded  by  the  Moon- Anchor  mine,  at 


THE    FORMATION    OF    BONANZAS    IN    GOLD-VEINS. 


15 


Cripple  Creek,  in  1899.  This  is  illustrated  in  Fig.  1.  The  ore 
in  the  mine  occurs  in  a  lode-channel  marked  by  a  band  of 
fractured  andesite  breccia.  At  the  400-ft.  level  a  small  dike 
(EF)  of  granite,  2  to  6  in.  thick,  intersects  the  lode-channel  at 
a  place  where  a  counter-fracture  (CD)  also  traverses  it.  A 
triangle  is  produced  by  these  intersections,  and  the  ore  is 

FIG.  1. 


FORMATION    OF   ORE 
AT  INTERSECTION    OF    FRACTURES 

SCALE.  ABOUT  30'=  1  IN. 


ORE 

\  CROSS  DIKE 


MOON   ANCHOR   MINE,   CRIPPLE    CREEK. 


ANDESITE  BRECCIA 

Bormat  *  Co..  X.T. 


proved  to  surround  a  block  of  ground  which  is  also  mineralized, 
but  not  sufficiently  so  to  be  regarded  in  its  entirety  as  pay-ore. 
At  the  crossing  of  the  dike  and  cross-fractures  a  very  rich 
body  of  telluride-ore  was  encountered. 

This  reminds  me  of  the  Yankee  Girl  ore-body,  mentioned 
by  Emmons.*     This  body  of  ore  was  of  phenomenal  richness, 


"The  Secondary  Enrichments  of   Ore-Deposits." 
edition. 


Page  19  of   pamphlet 


16  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

many  ten-ton  lots  being  shipped  which  carried  7  or  8  ounces  of 
gold  and  3000  to  4000  ounces  of  silver  per  ton.  The  ore  was 
also  rendered  remarkable  by  carrying  the  rare  mineral  stro- 
meyerite,  a  sulphide  of  silver  and  copper.  Mr.  Emmons  speaks 
of  the  bonanza  turning  into  low-grade  pyritic  ore  as  depth  was 
attained.  I  may  add*  that  this  change  was  not  gradual,  but 
sudden,  and  coincident  with  certain  structural  relations.  At 
the  surface,  the  vein  consisted  of  comparatively  low-grade  ore, 
which  led  to  the  finding  of  a  nearly  vertical  "  chimney,"  aver- 
aging only  25  to  30  ft.  in  diam.,  of  extraordinarily  rich  ore, 
consisting  of  the  copper  sulphides,  bornite  and  erubescite,  with 
stromeyerite  and  barite.  The  gold  in  the  ore  was  associated 
with  the  barite.  From  the  second  to  the  sixth  level,  at  about 
500  ft.  below  the  surface,  this  bonanza  proved  immensely  pro- 
ductive; then,  suddenly,  a  flat  floor,  dipping  W.  and  accompanied 
by  clay,  crossed  the  deposit.  This  flat  vein  was  worked  for  90 
ft.,  from  the  south  drift  at  the  No.  6  level,  and  contained  ore 
similar  to  that  of  the  Yankee  Girl  chimney.  The  latter  was  found 
again  deeper  down,  and  out  of  its  former  line  of  descent,  but 
it  was  much  diminished  in  richness,  and  appeared  to  merge  into 
the  general  body  of  low-grade  copper  and  iron  pyritesf  which 
characterized  the  lode  at  the  tenth  level.  This  mine  and  its 
neighbors,  the  Robinson  and  Guston,  are  idle  now.  They  are 
in  the  andesite  breccia  of  the  San  Juan  region.  The  Yankee 
Girl  chimney  was  situated,  I  believe,  at  the  crossing  of  three 
lode-fractures,  appearing  as  breaks  in  the  andesite,  which  was 
bleached  and  mineralized  where  they  traversed  it.  It  was  a 
curious  feature  of  this  mine,  and  of  the  Guston  also,  that  the 
short,  very  rich  bonanzas  of  the  upper  levels  gradually  lost 
their  definition,  that  is  to  say,  they  became  no  richer  than  the 
intervening  portions  of  the  lode.  This  was  interpreted  as  a 
"  lengthening  "  of  the  ore-shoots,  which  may  be  true,  viewed 
in  one  way ;  but  I  think  that  it  should  be  more  properly  re- 
garded as  an  impoverishment  of  the  lode,  marked  by  a  disap- 
pearance of  the  bonanzas.  The  surface-waters  of  these  mines 
are  very  acid,  as  -Mr.  Emmons  remarks.  At  the  Yankee  Girl 
mine  it  became  necessary  to  encase  the  pipes  in  redwood,  brought 

*  From  notes  made  during  an  examination  of  the  mine  in  January,  1892. 
f  Assaying  20  to  60  ozs.  silver,  1  to  4  dwts.  gold,  5  to  15  per  cent,  copper. 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS.  17 

from  California.  I  found  that  the  water  issuing  from  a  shallow 
adit  (73  ft.  below  the  collar  of  the  shaft)  readily  precipitated 
copper  on  scrap  iron.  Ore-forming  agencies  were  evidently 
still  at  work. 

California. — In  California,  especially  in  that  mining  region 
which  follows  the  foothills  of  the  Sierra  Nevada  and  traverses 
the  counties  of  Amador,  Calaveras  and  Tuolumne,  the  occur- 
rence of  pockets  of  rich  ore,  full  of  native  gold,  is  a  notable 
feature  of  the  superficial  parts  of  the  quartz-veins.  These 
pockets  appear  to  be  confined  to  the  zone  between  the  surface 
and  the  water-level,  and  to  be  dependent  upon  the  results  pro- 
duced by  the  small  cross-veins  which  encounter  the  main  lodes. 
In  1887  I  had  the  pleasure  of  extracting,  in  two  hours,  a  little 
over  170  ounces  of  gold,  worth  about  about  $3000,  from  one 
of  these  pockets.  It  was  at  the  Rathgeb  mine,  near  San  An- 
dreas, in  Calaveras  county.  The  main  lode  consisted  of  5  to  8 
ft.  of  massive  "hungry-looking"  quartz,  the  foot-wall  of  which 
was  a  beautiful  augite-schist  and  the  hanging  a  hard  diabase. 
The  water-level  was  160  ft.  below  the  surface.  Down  to  this 
point,  the  country  was  oxidized,  the  hanging-wall  exhibiting 
only  slight  alteration,  while  the  schist  of  the  foot-wall  was  soft- 
ened and  decomposed  almost  to  a  clay.  This  was  traversed  by 
numerous  small  veins,  which  appeared  to  act  as  "  feeders," 
forming  bunches  of  rich  ore  where  they  encountered  the  main 
lode.  At  the  120-ft.  level,  south  from  the  shaft,  there  were  some 
old  workings ;  and  the  examination  of  these  led  to  the  discovery 
of  a  small  seam,  about  one-sixteenth  of  an  inch  thick,  filled 
with  red  clay  which  carried  a  good  deal  of  native  gold,  as  was 
proved  by  washing  it  in  a  pan.  An  experienced  miner  was  put 
to  work,  with  instructions  to  follow  this  small  streak.  It  varied 
in  thickness,  and  occasionally  opened  out  into  small  lenticular 
cavities,  containing  a  clay  in  which  the  gold  was  distributed 
like  the  raisins  in  a  pudding.  Each  of  these  "  pockets  "  yielded 
several  hundred  dollars'  worth  of  gold.  At  length  the  streak 
widened  to  6  or  8  inches  of  quartz,  lined  with  clay.  The 
amount  of  red  clay  commenced  to  increase ;  coarse  gold  be- 
came more  frequent ;  and  a  big  discovery  was  hourly  expected. 
It  was  finally  made.  The  vein  suddenly  became  faulted,  and 
at  the  place  of  faulting  there  was  a  soft,  spong,  wiry  mass  of 
gold  and  clay — more  gold  than  clay.  The  first  handful  I  broke, 


18 


THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 


while  yet  the  stope  was  thick  with  powder-smoke,  contained 
three  ounces  of  gold.  Within  the  next  two  hours  this  pocket 
gave  us  $3000,  and  during  the  following  week  it  yielded  over 


FIG.  2. 


CROSS  SEAM 

OCCURRENCE    OF   A  'POCKET.' 


$20,000,  an  amount  which  was  obtained  at  a  total  cost  of  less 
than  $200.  When  it  had  been  worked  out,  it  was  easy  to  ob- 
serve the  conditions  which  determined  its  occurrence  at  this 
place,  as  Fig.  2  will  explain.  The  vein,  AC,  had  been  faulted 


THE    FORMATION    OF    BONANZAS    IN    GOLD-VEINS.  19 

about  its  own  width,  namely,  10  inches,  by  a  small  cross-seam, 
DE,  and  at  this  intersection,  B,  the  pocket  lay.  The  gold  was 
spongy  and  was  intermixed  with  quartz.  The  clay  which  pene- 
trated the  whole  mass  was  partly  red  and  ochreous,  and  partly 
a  gray  gelatinous  material.  In  the  quartz,  and  associated  with 
the  gold,  there  were  acicular  black  crystals  of  pitch-blende 
(uraninite),  together  with  uranium  ochre.  This  association  of 
gold  with  uranium  is  uncommon. 

New  Zealand. — Intersections  which  coincide  with  enrichments 
form  a  notable  characteristic  of  the  Hauraki  gold-field*  in  the 
north  island  of  2Tew  Zealand.  In  this  district  the  occurrence 
of  patches  of  native  gold  is  an  important  feature  of  the  regular 
mining  operations.  When  I  was  there,  in  1891,  each  stamp- 
mill  had  its  "  specimen-stamp,"  a  single  stamp  working  in  a 
separate  mortar,  and  employed  solely  for  the  treatment  of  speci- 
men-ore. These  rich  patches  occur  at  the  places  where  the 
u  reefs  "  or  lodes  cross  bands  of  flinty  quartz.  The  latter  are 
known  among  the  miners  as  "  flinties."  They  vary  in  thick- 
ness from  a  few  inches  to  mere  threads  of  chalcedonic  quartz. 
They  are  barren  in  themselves,  but  have  a  favorable  effect  on 
the  gold-veins.  The  latter  are  also  intersected  by  cross-veins, 
producing  an  enrichment  similar  to  that  caused  by  the  "  flint- 
ies." Fig.  3  is  a  sketch  of  one  of  these  intersections,  as  seen 
by  me  in  the  Moanataeri  mine.  The  lode,  AB,  consists  of 
a  series  of  small  seams  of  quartz,  conforming  to  the  struc- 
tural lines  of  the  enclosing  country,  which  is  hornblende-ande- 
site.  The  cross-vein,  CD,  is  a  band  of  soft  gray  decomposed 
rock,  which  also  carries  a  number  of  small  quartz-seams,  but 
only  near  its  crossing  with  the  main  lode,  AB.  The  line 
of  CD  is  parallel  to  a  large  fault,  to  be  seen  elsewhere  in  the 
mine-workings.  The  "  leaders,"  or  quartz-seams,  in  AB  are 
gold-bearing,  and  exhibit  marked  enrichment  at  the  intersec- 
tion with  CD. 

The  prevailing  formation  of  this  mining  district  is  an  ande- 
site,  which  is  traversed  by  soft  bands  of  decomposition,  called 
"  sandstone  "  by  the  miners.  The  latter,  when  penetrated  by 
quartz-seamSj  are  favorable  to  the  finding  of  ore.  The  gold- 
occurrence  is  essentially  sporadic  and  dependent  upon  local  en- 

*  It  is  also  known  as  the  Thames  district. 


20 


THE    FORMATION    OP    BONANZAS    IN   GOLD-VEINS. 


richments,  such  as  have  been  described.  The  district  is  sur- 
rounded by  thermal  springs,  and  is  near  the  well-known  volcanic 
region  of  Tarawera,  which  was  active  in  1884.  The  mine- 
waters  are  heavily  mineralized  and  very  acid,  so  that  the  metal 
screens  used  in  the  mills  are  quickly  corroded.  Tellurides  and 
selenides  of  gold  have  been  detected  in  the  ores ;  but  the  pre- 

FIG.  3. 


ENRICHMENT   AT   INTERSECTION   MOANATAERI    MINE,    NEW    ZEALAND. 

cious  metal  is  usually  found  native  and  in  coarse  particles, 
which  are  frequently  coated  with  native  arsenic.  The  district 
is  one  which,  I  think,  if  thoroughly  examined,  would  afford 
many  suggestions  regarding  ore-deposition.* 

*  The  best  description  which  has  come  under  my  notice  is  "  The  Geology  of 
the  Thames  Goldfield,"  by  James  Park,  read  before  the  Auckland  Institute,  1894. 

See  also  "  On  the  Kocks  of  the  Hauraki  Goldfields,"  by  F.  W.  Hutton,  Proe. 
Austral.  Assn.  Adv.  Sci.,  1888  ;  and  J.  R.  Don,  "  The  Genesis  of  Certain  Auriferous 
Lodes,"  Trans.,  xxvii.,  584-589. 


THE  FORMATION  OF  BONANZAS  IN  GOLD-VEINS.  21 

CONCLUDING  REMARKS. 

It  is  to  be  hoped  that  the  recent  recognition  of  the  agencies 
which  bring  about  the  formation  of  enrichments  by  surface- 
waters  will  not  cause  too  violent  a  swing  in  the  direction  of  a 
sweeping  advocacy  of  the  general  efficiency  of  descending 
solutions  to  form  ore-bodies.  The  study  of  the  problems  of 
ore-occurrence  has  been  hindered  in  the  past  by  such  reactions 
from  one  extreme  view  to  its  opposite.  Therefore,  in  conclud- 
ing this  contribution  to  the  discussion  of  the  results  produced 
by  descending  surface-waters,  I  would  emphasize  the  wider 
agency  of  ascending  solutions  in  forming  the  ore-masses  amid 
which  such  secondary  enrichments  are  occasionally  found.  It 
is  agreed  that  the  sulphide-ores  are  primarily  deposited  from 
ascending  waters ;  it  is  also  likely  that  such  a  result  is  repeated. 
A  region  once  subjected  to  fracturing,  which  has  permitted 
the  subsequent  passage  of  mineral-bearing  solutions,  is  likely, 
at  a  later  period,  to  be  subjected  to  a  repetition  of  these  activi- 
ties. The  geological  history  of  many  mining  regions  gives 
clear  evidence  of  a  repeated  disturbance  of  structure.  This  is 
indicated  by  the  existence  of  several  systems  of  fractures 
crossing  each  other,  the  later  ones  dislocating  the  earlier.  It 
is  probable  that  each  period  was  marked  by  mineralization,  the 
character  of  which  may  have  varied.  The  banded  arrange- 
ment of  the  lodes  of  certain  districts,  such  as  Freiberg,  Rico 
and  Butte,  suggests  this.  Enrichment  may  have  been  caused 
by  mere  addition ;  the  introduction  of  other  metals  may  have 
changed  the  average  composition  of  the  ore  in  the  lode  so  that 
it  is  now  extremely  valuable,  whereas  before  it  may  have  had 
no  economic  importance ;  a  silver-ingredient  may^  have  been 
added  to  the  gold-contents,  or  the  addition  of  copper  may  have 
made  a  deposit  doubly  valuable  by  improving  its  metallurgical 
character.  I  hope  the  present  discussion  on  ore-deposition  will 
prove  as  inspiring  to  further  investigation  as  did  Posepny's 
paper  of  1893,  and  that  data  concerning  the  possible  secondary 
enrichment  of  sulphide-ores  by  the  repetition  of  ascending 
solutions  will  be  sought  for.  There  is  nothing  like  a  working 
theory  to  sharpen  the  observation.  Theories  do  not  alter  facts, 
but  they  often  lead  us  to  tind  new  ones. 

In  cordially  welcoming  the  splendid  treatise  of  Professor 
Van  Hise  I  need  make  no  reservation.  When  Posepny  made 


22  THE    FORMATION    OF    BONANZAS    IN   GOLD-VEINS. 

clear  the  essential  character  of  the  upper  or  "  vadose  "  water- 
circulation,  he  did  us  a  great  service ;  and  when  he  combated 
"  lateral  secretion  "  he  overthrew  a  very  narrow  interpretation 
of  ore-formation,  which  was  calculated  to  hinder  seriously  our 
progress  toward  the  understanding  of  these  difficult  problems. 
But  Posepny  was  carried  so  far  by  his  controversy  with  Sand- 
berger  as  to  over-emphasize  the  sole  agency  of  ascending  cur- 
rents. At  that  time,  in  1893,  I  demurred  to  this  extreme  view 
and  said, "  the  word  circulation  is  the  key  to  the  whole  matter.'7* 
By  this  I  meant  that  the  entire  underground  water-circulation 
played  a  part  in  the  formation  of  ore,  and  that  to  swing  from 
one  portion  of  that  circulation  to  another,  restricting  oneself  to 
the  agency  of  either,  would  not  (so  it  seemed  to  me  from  ex- 
perience in  the  mines)  solve  the  problem. 

It  does  not  appear  to  me  that  Professor  Van  Hise  has  erred  by 
exaggerating  any  particular  view  of  the  subject.  His  elucida- 
tion of  the  water-circulation  as  a  complete  system  is  based  on  a 
broad  conception  of  the  whole  matter.  Of  course,  in  indicating 
the  work  done  by  an  agency  hitherto  largely  overlooked,  he  was 
compelled  to  place  some  emphasis  on  certain  neglected  features 
of  the  descending  portion  of  the  water-circulation,  and  thus  to 
give  it  some  prominence  in  his  masterly  analysis.  This  makes 
the  consideration  of  the  question  of  secondary  enrichments  by 
surface-waters  one  of  the  most  valuable  parts  of  his  treatise. 

Regarding  this  question  of  secondary  enrichment,  it  is  to  be 
pointed  out  that  all  ore-deposits  are  "  secondary,"  the  ore  as 
found  by  the  miner  being  merely  the  last  term  of  a  series  of 
solutions  and  precipitations  through  which  its  substance  has 
passed  in  a  ^constant  shifting  due  to  the  underground  water- 
circulation.  However,  the  last  stage  of  the  journey  is  the  only 
one  of  immediate  importance  to  the  miner ;  and  the  determi- 
nation of  the  causes  which  brought  it  there  is,  to  him,  far  the 
most  interesting  aspect  of  the  general  inquiry.  That  Mr.  Em- 
mons  should  also  have  investigated  and  illuminated  the 
problem  is  matter  of  much  pleasure  to  a  great  many,  engaged 
in  mining  throughout  the  West,  to  whom  his  geological  con- 
tributions have  always  seemed  to  possess  a  practical  bearing 
and  value  unfortunately  not  always  found  in  scientific  descrip- 
tions of  geological  phenomena. 

*  Trans.,  xxiv.,  950. 


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